1970 Muncie cases and assembly stamps

[Steven S.]

I don't have a 1970 TIMJG handy and perhaps this info may be in it, but what is known about the 660-661 case changeover? Also, I'm seeing some assembly stamps with an extra alpha character at the end, such as "P9D09BD", and another example "P9H25AE". Both of those examples are on 660 cases with 1970 vin stamps, and both examples the extra character appears to have been loose stamped. Anyone shed some light on this?

Thanks,
Steve

[Eric D.]

Re: 1970 Muncie cases and assembly stamps

I have several examples of P0MXXX (AUG. 1969) 660 main cases, and P0PXXX (SEPT. 1969) 661 main cases...
The extra alpha characters your talking about(plus a few you haven't talked about) I don't know, still studying those...

Hope this helps... Eric

[Steven S.]

Re: 1970 Muncie cases and assembly stamps

Eric, thanks for taking the time to reply. Take a look at these two examples;

http://pages.ebay.com/link/?nav=item.view&alt=web&id=291395795356

http://pages.ebay.com/link/?nav=item.view&alt=web&id=391022702790

It just so happens these two transmissions are from cars only 51 apart on the line, the later of the two getting the 660 case. Also notice the assembly stamp on the 660 case is P9xxxx. Ironic that both are on eBay at the same time.

Steve

[Leif A.]

Re: 1970 Muncie cases and assembly stamps

Eric, thanks for taking the time to reply. Take a look at these two examples;

http://pages.ebay.com/link/?nav=item.view&alt=web&id=291395795356

http://pages.ebay.com/link/?nav=item.view&alt=web&id=391022702790

It just so happens these two transmissions are from cars only 51 apart on the line, the later of the two getting the 660 case. Also notice the assembly stamp on the 660 case is P9xxxx. Ironic that both are on eBay at the same time.

Steve

Red flag to me is the fact that the pictures of the second M21 were taken in March 2011. Wonder what that trans looks like today??

[Eric D.]

Re: 1970 Muncie cases and assembly stamps

Steve, The first ebay trans w/660 case could have been left over from the 1969 model year(kind of a stretch) but 1970 model year used different side cover. The pictures don't show any of the other know VIN locations from other assembly plants, could be a re-stamp (glass bead hides a lot)...

The second ebay trans w/661 case looks real...

Hope this helps... Eric

[Steven S.]

Re: 1970 Muncie cases and assembly stamps

Eric,
I agree that anything is possible with the 660 case trans since it looks more suspect, what makes me a bit more biased towards accepting it as legit is I have in person seen another 660 cased transmission with similar features. This particular transmission (660 case) has the correct 1970 side cover, the same odd assembly stamp with extra character(P9D09BD), and has a 1970 vin with no funny business, non-corvette however. I think what this may be is one of those odd anomalies that is going to be difficult if not impossible to explain. The key may be in the meaning of those extra assembly stamp characters.

Thanks,
Steve

[David L.]

Re: 1970 Muncie cases and assembly stamps

When I bought a white "early" 63 SWC (#1450, Oct. 1962) in the late 1980's it had a 67 Chevrolet 327 engine and "late" 69 Camaro Z28 Muncie. The 69 Camaro production ended in Nov. 1969.
The casting numbers on the Muncie were are follows:
Main case "3925660"
Side cover "3950306"
Tail Ext. "3857584 GM"
The stampings were as follows:
"P9M20" (4 Spd. Muncie, 1969 model year, August, 20th of the month)
"9 N 606152" (partial VIN, 1969 model year, Norwood plant where Camaros were made)
Tag "3950356"

Dave

[Eric D.]

Re: 1970 Muncie cases and assembly stamps

Dave, I checked the Camaro VIN you listed, It was built Feb. of 1969 so the trans has to be built Aug. 20th of 1968(if original to the Camaro)...

An Aug. of 1969 Muncie would have the A-B-C ratio indicator at the end of the P#...

Aug. of 1969 Muncie was still using 660 Main cases, but you will find these all have drilled and tapped drain plugs...

Aug. of 1969 started the 1970 model year, and all 1970 and later Muncie main cases have drain plugs...

Hope this helps... Eric

[David L.]

Re: 1970 Muncie cases and assembly stamps

Dave, I checked the Camaro VIN you listed, It was built Feb. of 1969 so the trans has to be built Aug. 20th of 1968(if original to the Camaro)...

An Aug. of 1969 Muncie would have the A-B-C ratio indicator at the end of the P#...

Aug. of 1969 Muncie was still using 660 Main cases, but you will find these all have drilled and tapped drain plugs...

Aug. of 1969 started the 1970 model year, and all 1970 and later Muncie main cases have drain plugs...

Hope this helps... Crash

Eric,

You are about right on the date when the Muncie originally from the 1969 Camaro (partial VIN 9N606152) was made. I just found a 1969 Camaro (VIN 124379N604331) currently on Ebay that has a body build date of "02D" (4th week of Feb. 1969). The Muncie transmission (stamped "9N606152" and "P9M20") indeed was an original 1969 Camaro (probably a Z28) as I believe that only Camaros and Firebirds were made in Norwood, Ohio, ("N" stamping) during the 1969 model year. I had assumed that the August 20th date ("P9M20") was in 1969 (which was wrong and should have been 1968 as you mentioned) since the first 1969 Camaro made in Norwood had a partial VIN of 9N500001. Upon further research the last 1969 Camaro made in Norwood was something like 9N71XXXX in November 1969. I believe that the 1969 Camaro production was the longest in GM history (Aug. 1968 to Nov. 1969).
The 1969 Firebirds would have a partial VIN with a "1" (or maybe even a "2") after the "N" (example: "9N100001).
Thanks for the correction.

Dave

[Eric D.]

Re: 1970 Muncie cases and assembly stamps

Dave, , The partial VIN for a Camaro would start 19NXXXXXX, Firebird 29NXXXXXX...

1= Chevy
2= Pontiac
3= Olds
4= Buick

I have over 100 complete Muncie cores in stock, and another 200 or so empty main cases in stock to study all the oddities of the Muncie 4-speeds...

1969 Corvette had a long production run also(Sept 1968 thru Dec. 1969)...

Hope this helps... Eric

[Joel A.]

Re: 1970 Muncie cases and assembly stamps

I have always been under the impression that the "extra" alpha codes at the end of the "P" codes were for what shift the trans was assembled on...1st, 2nd, etc. Don't know where I heard that, but I've believed it to be true for 30 years or more.

[Terry M.]

Re: 1970 Muncie cases and assembly stamps

Dave, , The partial VIN for a Camaro would start 19NXXXXXX, Firebird 29NXXXXXX...

1= Chevy
2= Pontiac
3= Olds
4= Buick

I have over 100 complete Muncie cores in stock, and another 200 or so empty main cases in stock to study all the oddities of the Muncie 4-speeds...

1969 Corvette had a long production run also(Sept 1968 thru Dec. 1969)...

Hope this helps... Eric

Eric,
1969 Corvette production began August 21, 1968 and ended December 18 or 19, 1969.

[Terry M.]

Re: 1970 Muncie cases and assembly stamps

I have always been under the impression that the "extra" alpha codes at the end of the "P" codes were for what shift the trans was assembled on...1st, 2nd, etc. Don't know where I heard that, but I've believed it to be true for 30 years or more.

Joel,
I don't know where you heard that either because according to the 1969 model year Information Bulletin that Chevrolet circulated to their dealers the suffix codes indicate type of transmission:

A = 2.52:1 wide ratio M20
B = 2.20:1 close ratio M21
C = 2.20:1 HD "rock crusher" M22

No other letters were called out by Chevrolet in their information supplied to their dealers as far as I know.

[David L.]

Re: 1970 Muncie cases and assembly stamps

Dave, , The partial VIN for a Camaro would start 19NXXXXXX, Firebird 29NXXXXXX...

But apparently not on the transmissions. The partial VIN on the original 4-speed Muncie in my 1966 Corvette starts with the model year ("6" for 1966 and "S" for St. Louis).

[Joel A.]

Re: 1970 Muncie cases and assembly stamps

Terry, I was referencing the EXTRA characters mentioned in this thread, the "P9D09BD", and "P9H25AE", not the A-B-C ratio call-outs.
As I said, don't know if it's true, and couldn't prove it one way or another....just something I "learned" a hunnert years ago.