1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

[Richard M.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

I've come to the realization that RPO 565 is one of those mysteries we may never solve unless we find someone who worked at St Louis in the late 50's who can reveal the details. Inasmuch as I and others are eager to get factual evidence of it's physical existence and details, we may discover it's a simple paperwork thing or uneventful feature or truly useless information. However, for Chevrolet to go through all of the trouble to list it and include it in just a few cars certainly makes it interesting and archaeologically challenging.

Here are the present pieces of information, RPO 565 Quantities, and "Speculations" based on what we know....

AIM References RPO 565, AMA Specs, etc

1957 - AIM None, AMA Spec No
1958 - AIM None, AMA Spec "Underbody Equipment"
1959 - AIM Body Service List, AMA Spec No
1960 - AIM None, AMA Spec "Body Equipment (Service)" with notation "Revised February 1960"
1961 - AIM Body Service List, AMA Spec No

RPO 565 Name & Quantities Built

1957 - Body Equipment 5
1958 - Body Equipment 0
1959 - Body Equipment 1
1960 - Body Equipment 3
1961 - Body Equipment 1

Speculations....

Trim or Emblem Delete
Chassis/Suspension modifications/alterations
Engine Related modifications/alterations
Body Repairs modifications/alterations for special features

My personal speculation is that whatever this RPO entails, it may have been dependent on other RPO features of the car assembly. It may have to do with Exterior, with or without Hard Top or Soft Top, Interior Trim Combinations, Colors, Chassis Standard or Heavy Duty Suspensions, Brake features, Engine features, etc etc. Basically a myriad of possibilities.

Rich

[James G.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

David, I agree. Published prior data(Spec Guide, Noland's book, etc) says 43 RPO 579 "Airbox" cars and 51 RPO 684 HD Brake/Susp cars, which include the 43 Airbox cars, which would lead one to believe there were 8 RPO 684 cars without FI, i.e. with RPO 469C(2x4BC).

But A friend showed me some GM RPO data that conflicts with these numbers. It states 48 RPO 684 cars also. That would leave 5 BigBrake cars without FI. Most likely, they would be the 270HP Duntov Cam cars. I too doubt they'd be base engine Powerglides. I see that because there were 5 1957's built with RPO 565 becomes a thought now too. Coincidence?... Maybe. Factual?... I think more data could help.

....Something just hit me while writing this. In looking at the 1953-1967 Spec Guide, I always wondered where the suffix letters came from, shown for RPO's 469, 470, and 579. A,B,C E,F...... THOSE are the single letter ECL's, are they not? How did the Spec Guide Author(s) and Noland in his C1 book decipher those? I'm eager to know. Maybe they had some cross reference list. This is the primary reason I posted..... What these suffixes represent.

Your assessment of the 48 RPO 684(HD Brake/Susp) cars minus the 43 RPO 579(Airbox/FI) leaving 5 possible RPO 469C(2x4BC) cars now makes much more sense to me. However, I tend to think that those 5 wouldn't have any special "Body Equipment" due to the BigBrake option. Wouldn't they just follow the RPO 684 AIM instructions to build them? That clearly shows the body modifications for ductwork, etc, right?

Coincidentally, I recently looked at a 1957 RPO 684 "long time stored" car. It's NOM so no engine data to help. I'll have to also freshen up my 1957 skills....Did the Duntov Cam cars use a dash mounted High RPM tach? I've learned a little bit about the Airbox cars and know they used the column mounted tach. I'll have to look and also look really close at the front crossmember to see if any evidence of orange painted numbers are there. That'd be quite interesting. I'm going to be in the area of the car tomorrow.

Rich
edit....PS You may want to send a Email or PM to Rich Mauser,

https://www.forums.ncrs.org/member.p...Mauser-(27974)

who owns the '59 with the 1-of-1 RPO 565 to get more details about his car.

57 Vin #6338 is the old ART SAYLER race car. 270hp with 684. Fully documented. Lives now in Pennsylvania. It is the only 270hp car I know. I am sure there are others. There appears to be more than 10 real 684 fuel injection cars with NO AIR BOX, and ducting thru the rockers.

And of course, many FI cars with ''added' brakes and suspension with NO DUCTS. A racer friend said he bought his SEBRING KIT for $202 at his friendly Chevrolet dealer in 1960. It came in a big wooden box, and had front and rear H.D. Springs, front hubs, 4 finned drums, quick steering adapter, screened backing plates for all 4 wheels, cedremetalic linings and special wheel cylinders. He bought the RPO 276 wide wheels for $18 each.

We all need to sit around the campfire with our records and have a discussion. Every year we lose more people that talk this knowledge to the grave.

[David B.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Jim,
With all due respect I do not buy your comment that 10 real 684 FI cars with no air box exist. If that were true we might just as well throw out all Chevrolet production records. Personally, I prefer to believe original Chevrolet records.

[James G.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

I agree David. The problem I have is the ''RECORDS'' have never been shared. I don't have any copies of 1957 data. I am glad you have copy. I will love to share with you my ''own'' 1957 RPO 684 cars. Any many of them are known in the hobby, but never inspected. Are the ''production records'' available? The Black Book by Mike Antonick has been the published record for years.

[David B.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Jim,
Here is the production breakdown for RPO 684 optioned 57 Corvettes:
RPO 684
H.D. Brake & Susp. (2900)
A 2
B 10
C 3
D 10
E 17
F 6
Total 48
This breakdown leads back to the original question Rich asked about what does the letter A, B, C etc. represent? My response was and still is they are not consistent letters meaning the same for other options. In the case of RPO 684 the car had to be ordered with: 3 or 4 spd trans, 270HP or FI and have positraction with 3.70, 4.11 or 4.56 ratio. As evident from the 684 production breakdown each letter represents a particular group of Corvettes equipped with similar options ei: A --- might be cars with 3 spd., FI & 3.70 posi As mentioned these letters do not always mean the same thing for other options which make it imperative to have other GM documentation to interpret. P 170 of the 56-57 JM states all 43 air box cars had RPO 684 I have always blindly accepted this as fact. After taking a real close look at RPO 684 production it makes me think that PERHAPS your survey may be right and (GOD FORBID!) not all 579D/E optioned cars were equipped with 684.
Have not been involved in a good street fight for a long time but get the feeling this thought could lead to one.

[Loren L.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Forgetting RPO 565 for the moment and focusing on the six divisions under 684, what would be the criteria for "separating" a category out? Would it be decision-making "on the line"?, ie softop only, hardtop only, two tops? It would seem that 3 spd vs 4 spd and rear axle ratio are "off the main line" and done at one location; what other item would be critical and somewhat involved? Radio? A=s Radio & 2 tops, B =s radio & softtop only, C =s radio & hardtop only, D =s NO radio & softtop, E =s NO radio & hardtop only and F =s NO radio & 2 tops. Fit the codes however you like, and maybe radio and tops are NOT the criteria.....but does the theory fit?

[David B.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Loren,
I am not sure there was a criteria. As for RPO 684 and seeing other option breakouts I would venture a guess that it would be tied primarily to sales (that was the primary reason for keeping production data in the first place). Since this is a HD option I would not consider radio or heater or any other comfy option in my count since most if not all 48 cars probably were not so equipped. MY guess in this particular instance would be gear ratio, 3 or 4 spd. and 270HP vs FI. Looking at the break down numbers I would guess B, D, E, & F are the 43 air box cars with the following :
F 6 with 4.56 E 17 with 4.11 D 10 with 3.70 and B 3 spd. with 3.70 the two remaining A 2 and C 3 are in all likelihood your 270HP vs FI cars that are non air box equipped, take your pick as to which one goes where. My guess only and at this time cannot verify I am correct. Your a smart guy Loren what are your thoughts?

[Loren L.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

I just keep poking at it with a long stick, I guess. Rear gears, I think are more likely than 3 spd vs 4 spd; 4.56 =s drag car, 4.11 =s road racer & 3.70 =s city cruiser/road racer. What was the group that put that book together? Any names available of people thanked for their input? Maybe it's time to contact the Sun City GM retirees.....

[Richard M.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

David, Loren,

Interesting analyses....

I got out my 1929 to 1959 P&A Catalog which lists every Model Series from 1929 to 1959 with Prefix letters for each model#.

For Corvette, we know
1953-1957 = E (2934)
1958-1959 = J (800)
1960-1962 = ?? not listed

See below for Model Series Letter Prefixes. I admit it gets confusing for 2 character Prefixes.

David, Could you see if any of these coincide with your RPO data? Could this have anything to do with the "ECL" designations? Or am I getting "colder"?

edit....if too small I can PM to you .....or right click, open in new tab/window, Ctrl + to enlarge, Ctrl 0(zero) to reset.

Rich

[Cecil L.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Interesting thread.
One of my other interests is sorting out the history of the 348/409 "W" engines. It's a real challenge since there is so much incorrect info out there.
Anyway, in my research I found this page from the 1960 Chevrolet specs showing the engine options along with the model exception codes for those options. Being familiar with the Corvette use of ECL codes I was intrigued but was never able to find the key to decoding them. I am assuming that model exception codes were used similarly to ECLs. Apparently the exception coding system was used long before I realized. I did figure out how to decode/read the IBM punch cards, though.

[Richard M.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Interesting thread.
One of my other interests is sorting out the history of the 348/409 "W" engines. It's a real challenge since there is so much incorrect info out there.
Anyway, in my research I found this page from the 1960 Chevrolet specs showing the engine options along with the model exception codes for those options. Being familiar with the Corvette use of ECL codes I was intrigued but was never able to find the key to decoding them. I am assuming that model exception codes were used similarly to ECLs. Apparently the exception coding system was used long before I realized. I did figure out how to decode/read the IBM punch cards, though.

Cecil, Interesting info. THose Xx codes are interesting....for High Perf Engines and HD PG transmissions. Hmm, I see a hint there. Thanks for sharing that doc. I believe that the Exception Letter designation in you page is the same thing as ECL...... Exception Control Letter.

IBM punch cards? Me too, on a IBM 360 at College looooong ago, then Paper Tape on DEC PDP8's when technology advanced in the 70's. Goes way back doesn't it.

Rich

[Cecil L.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Rich,
I was referring to the Fisher Body IBM punch cards used for chevy production orders.
A little more research shows that the ECL codes are the parts list code for the particular RPO,
For instance:
A 1961 348 250 HP engine suffix code F, part#3782835 RPO code 576 with a standard trans would be a parts list A resulting in an RPO 576A showing on the build documents.
The same RPO 576 engine, suffix code H, prt # 3764963 with a turboglide is parts list B thus RPO 576B on the build sheet.
I have been looking for some document with the various parts lists to decode these things but so far have not had any luck. Meanwhile I just keep collecting TSB's CSN's, and any Chevrolet Dealer correspondence I can find. Maybe someday we'll figure it out.

[Richard M.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Rich,
I was referring to the Fisher Body IBM punch cards used for chevy production orders.
A little more research shows that the ECL codes are the parts list code for the particular RPO,
For instance:
A 1961 348 250 HP engine suffix code F, part#3782835 RPO code 576 with a standard trans would be a parts list A resulting in an RPO 576A showing on the build documents.
The same RPO 576 engine, suffix code H, prt # 3764963 with a turboglide is parts list B thus RPO 576B on the build sheet.
I have been looking for some document with the various parts lists to decode these things but so far have not had any luck. Meanwhile I just keep collecting TSB's CSN's, and any Chevrolet Dealer correspondence I can find. Maybe someday we'll figure it out.

Cecil,

I see....And I see in your page the 1960 Corvette lists the single letter ECL's which are likely based on prior research by Noland and John Amgwert for the Spec Guide. I wonder where they got that info.

Yes it's frustrating that we can't seem to find anything re other early ECL definitions. It had to exist somewhere at some time in the past.

I wonder where the 1963 - 1967 ECL data came from when Noland wrote his C2 Guide? Also the authors of the 63-67 Trim Tag book, Al Grenning and Roy Sinor. Maybe they might check in here with some ideas. I'll see if I can get them to comment.

Thanks & HNY....
Rich
ps Did you work at GM/Chevrolet or in the industry related to ordering cars?

[David B.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

Cecil, Rich, Loren,
I believe the KEY to decoding these single digit numbers lies in assembly documents referred to as: Bill of Material and Parts list. I have had access to the 1956 version. Its purpose was to list all part numbers to be used in building a car. It included separate sheets for each option and in column form listed all part numbers to be added for that particular option and in another column listed all the part numbers to be deleted. If you can visualize 10 column accounting paper with single digit letters (A,C,D etc.) at the top of each column it would spell out to the assembly line (supervisor?) what parts to used and in another column what parts to delete. I am sure this procedure was improved upon each year but the information required would still remain the same.

[Cecil L.]

Re: 1956 to 1962 Chevrolet and/or Corvette RPO Single Letter ECL Codes & RPO 565

David,
I believe you are correct and that is the Rosetta Stone we are looking for. I believe John H spelled out the process in one of his articles. The key must be what the person used to convert the dealer order forms to actual computer punch cards or whatever form was used in the earlier days for the parts lists that went to the assembly plants.
The 1960 page I posted is from the GM Heritage Center specs for the 1960 model year. It's the only year I've found with such a listing of engine ECL codes in their publications. I do have engine ECL codes for a few years of the 349/409 engines from the Tonawanda Engine Plant as I used for illustration in my post but still need the parts lists to sort it all out. Apparently every RPO had it's own ECL code as seen on the build sheets to indicate compatibility with other options.
So who has the Parts Lists?