Off Topic Post 69 GMC tow vehicle

[William H.]

Hello, I know this is off topic but it pertains to a possible tow vehicle so I hope it will be allowed. Maybe someone can direct me to a more appropriate forum for the discussion. I am looking at a 1969 GMC 1/2 ton truck. Acording to the glovebox build sheet it is an original 396/310hp, Turbo 400, A/C, P/B, P/S Car. I am trying to find the build date of the vehicle and determine if the 396 is the original motor.
The VIN is CE10D-SA144XX There is no serical number on the Block but the very clear pad with proper broach marks has the stamping T0918YN.
The block is cast H12 ? and the heads I 12 8. The heads are cast# 3933148 which is correct for the 69 two barrel 396. I could not make out the block casting number in the truck. There is a stamped steel tag rivited to the transmission marked CJ-69-3126 and seperately 263 Any help in dertiminig the originality of this set up would be appreciated. There is some rust in the cab but if this is indeed as originally equiped than I think I might go for it. Thanks in advance,
Bill

[William C.]

Re: Off Topic Post 69 GMC tow vehicle

Look for a VIN stamping on the block in the area of the Oil Filter, a fairly common location in the 1969 era.

[William H.]

Re: Off Topic Post 69 GMC tow vehicle

Thanks Bill,
I did that and couldn't see anything. Should it be on a machined flat surface or just on the cast part of the block? DO you know exactly where it should be? Also do you know for sure if this Year truck had the VIN derivitive on the engine? I thought someone once told me that only Corvettes had the VIN on the block and that other cars did not do so until a later date. Do you have any info on that idea?
Thanks again
Bill

[William C.]

Re: Off Topic Post 69 GMC tow vehicle

I believe by '69 GM was putting a VIN on everything, but not for certain about trucks. Typically it is on the vertical flange above the oil filter, just where the block mates to the bellhousing. Stamped right into the as cast surface, with pretty small number stamp set.

[Terry M.]

Re: Off Topic Post 69 GMC tow vehicle

I once owned a 1976 Suburban (Big Orange) with 454 that had the engine VIN derivative stamped on a tab about an inch above the front timing cover. I couldn't find it until I was overhauling the engine and had it on the stand.

I don't know if your earlier truck had the VIN derivative on the engine or not, but you might look for the tab just for grins. When I get home to my Chevrolet data I'll look for the YN code if someone else doesn't beat me to it.

[Clem Z.]

Re: Off Topic Post 69 GMC tow vehicle

I once owned a 1976 Suburban (Big Orange) with 454 that had the engine VIN derivative stamped on a tab about an inch above the front timing cover. I couldn't find it until I was overhauling the engine and had it on the stand.

I don't know if your earlier truck had the VIN derivative on the engine or not, but you might look for the tab just for grins. When I get home to my Chevrolet data I'll look for the YN code if someone else doesn't beat me to it.

the "lime book" does not list a YN code

[Terry M.]

[Clem Z.]

Re: Off Topic Post 69 GMC tow vehicle

Bill,

Sorry it took me so long to get back to you, but this stuff is not exactly handy.

YN shows 366 CID 4-speed LPG (Liquid Propane Gas), AIR (Air Injection Reactor) in a TE 50-60 Series Truck. TE is a tilt cab model.

Are you sure it is YN, and not YP or YQ? -- Those are 396 w/TH400 for CE 10-20-30 series trucks. YP has AIR, YQ does not. CE = conventional truck.

Your 1/2-ton, if a pick-up truck, would be CE 10.

Clem,
I got these from the Chevrolet Information Bulletins provided to the dealers in 1969 (and other years). Kind of like the TSB (Technical Service Bulletins) that they still produce. There were two Information Bulletins about ID codes in 1969, and the YN was only in the later one --April 14, 1969. The "lime book," and for that matter the TIM&JG, are secondary sources – that is they get their information from the material Chevrolet published. The Chevrolet material is a primary source. That is why Library and Archives are so important. Work with these things long enough and one finds out that even these primary sources are not complete or accurate in all cases – but that is a whole other story.

if it is a 366 cu inch it would be a "tall block" and this could be told by the .400 extra distance the block extends above the water pump flange

[William H.]

Re: Off Topic Post 69 GMC tow vehicle

Hello All,
thanks for the replys, I belive it must be YP As the owner showed me a list that showed it was a 396/310 th400. I was going from memory. I know that it was not YQ as that is what I was expecting to see when I got there as I had already looked it up online but did not see the YP listing. I already looked at the small half moon tab above the water pump. THere was nothing there I know that this is a common place for the VIN on Truck engines. I am going to go back ASAP to look at the oil filter area. I will verify the suffix again at that time. Any ideals about the build date of the truck based on the VIN ? IF the engine dates work with the Body Build date than I may go ahead and purchase.
Thanks again,
Bill

[Terry M.]

Re: Off Topic Post 69 GMC tow vehicle

You have me on body build dates for trucks. That's way outside my experience.

The only thing I can offer is what there is on some metal cars. The body trim tag sometimes has a letter/number combination that works out to month/week of the month. The month may be consecutive build months, just like trim tags on Corvettes, so one has to know when production started that year. I don't know where one finds that data, unless there is a truck forum on the web that is just as anal as we are. What are the odds of that?

The other thing is to do what C1 guys did for years: list all the dates for alternator, carburetor, transmission, differential/axle, engine, heads, intake, and glass. Put them all on a list and if those parts are original the dates will all be pretty close together and the body had to be built just after that. See how the engine assembly date falls in line with the rest of the dates. Odds are anything replaced will have a date that is obviously out of line. It's down and dirty, but it works.