# Help decode my 72 GTO



## etd66ss (Aug 19, 2018)

I'm might be looking to sell my 72 GTO, and I want to make sure it's is a #'s matching car before I list it as such. I have the PHS docs from the previous owner, and he insisted it was all original drivetrain.

Here is the trim tag: 

https://imgur.com/L66582m

Engine code:

https://imgur.com/vQ6lqoE 

Engine VIN (seems to be missing last 4 digits):

https://imgur.com/YmKvLQT

TH400 Identification plate:

https://imgur.com/02sVagE

TH400 stamping:

https://imgur.com/QqsOo9J

Axle code:

https://imgur.com/p53hzFb

I'm not seeing in the PHS docs how to ensure all these components are correct... The PHS docs say the engine is a YT, but my block is stamped YS, which is 1971. The trans seems to decode as 1971 as well? It's a first week of January build, could they have used a 1971 drivetrain?

I know GM had a strike in 72 and the GTO production numbers were really low, and I heard they scavenged for parts etc...


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## PontiacJim (Dec 29, 2012)

etd66ss said:


> I'm might be looking to sell my 72 GTO, and I want to make sure it's is a #'s matching car before I list it as such. I have the PHS docs from the previous owner, and he insisted it was all original drivetrain.
> 
> Here is the trim tag:
> 
> ...


Data tag is too blurry, but matches a 1972. The GTO was an option on the LeMans, Option Code W62.

Here is what my books say:
1972 GTO 2 Dr Ht Coupe - 5,673 made

YS for 1972 is the 400CI/Automatic. There is no YT for 1972.

Engine/Vin Number reads: 2=Pontiac D=LeMans 37+ 2-Dr Ht Coupe T=400CI 4 bbl carb Dual exhaust 2=Model year 1972 P=Pontiac, MI assembly plant 14= should be partial numbers of your VIN, but not complete. So if all that matches your VIN at the windshield, then I would say matching engine.

Heads should be 7K3 found on center exhaust port. This is the 250HP engine.

Axle code WFP is 3.23 ratio

TH400 should have a code "PG" which yours does not. Should also be stamped with your cars Vin. I see "PY" (V8-400 4 Bar. carb., GTO, LeMans, Firebird) which is listed for 1971 and was standard on 3.55-4.33 rear end ratios - so it may have the higher line pressure for firmer shifts. I would say it has been swapped. I believe it to be a 1970 transmission according to the date stamp "70" and the 20P of the serial number stamping with the "0" meaning 1970. It may have been a late 1970 trans installed in a 1971 car based on the "PY" code. Here is where I got this info: 1962-74 Pontiac Automatic Transmission Codes


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## etd66ss (Aug 19, 2018)

PontiacJim said:


> Data tag is too blurry, but matches a 1972. The GTO was an option on the LeMans, Option Code W62.
> 
> Here is what my books say:
> 1972 GTO 2 Dr Ht Coupe - 5,673 made
> ...


Thank you!

So I should not list the car as #'s matching then, even though it looks like a #'s engine. The partial VIN on the engine does match the VIN of the car.

I'm looking at my PHS docs, where they highlight what my car came with, and it clearly shows a 400 4 bbl YT L78 engine with a PX M40 transmission. There is no YS on this powertrain chart at all for 1972. For the rear end, it states 3.55 gears for non AC, and 3.23 with AC. My car is an AC car.


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## 11th Indian (Feb 15, 2018)

Very nice custom color. Metal Flake?


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## PontiacJim (Dec 29, 2012)

etd66ss said:


> Thank you!
> 
> So I should not list the car as #'s matching then, even though it looks like a #'s engine. The partial VIN on the engine does match the VIN of the car.
> 
> I'm looking at my PHS docs, where they highlight what my car came with, and it clearly shows a 400 4 bbl YT L78 engine with a PX M40 transmission. There is no YS on this powertrain chart at all for 1972. For the rear end, it states 3.55 gears for non AC, and 3.23 with AC. My car is an AC car.


Hmmm, very interesting. I am using the *GTO* Association of America ID Guide and it does not list the YT engine code BUT, when I go to the Wallace Pontiac engine codes, I do see a YT code for the 250HP 400: Pontiac Engine Codes

So next I pull up my Pontiac engine book by Pete McCarthy and here is what I find- Both engines are identical 250HP/automatics and are the only engines used in the A, B, F, & G model lines - or all body styles. Other engine codes are specific to just a model line or a couple of model lines. So the engine seems to be a common engine for 1972. Again, no YT code for 1971.

The next thing you need to do to answer a few questions is to look at the back of the block near the distributor. You will find the year (typically a 2 digit casting number) and the date code as to when the block was cast. This should be close to your build date as should the date codes on the 7K3 heads.

I can't help much on the transmission other than what I have already provided.

I don't think all the plants went on strike, just the Norwood, Ohio plant which made the Firebird line. I don't think it affected the A-body Lemans. I read that to get as many as they could out the door after the strike ended and before the 1973 year models came out, they cut corners and did not undercoat them and just painted the exterior. I looked at a 1972 Firebird Formula 400 that a guy wanted to sell cheap, but was rusted very badly from the inside out - door jams were blowing out, so it made sense that they just threw these cars together. It really needed a complete body to save it. https://www.nytimes.com/1972/09/28/...is-ended-at-plant-in-ohio-after-174-days.html

I would contact PHS noting your build sheet and what you have found with your car. He would be better qualified to give you a definitive answer as he has seen build sheets that don't seem to match for one reason or another.

It seems odd that the engine appears to match the car, yet has the wrong letter code. Possibly the block was mis-stamped or the Pontiac paper is wrong, especially if there really is no difference in the engines. 

So I would wait on PHS before advertising the car as original/non-original numbers. Also check the block dates.


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## etd66ss (Aug 19, 2018)

OK, so here are the intake numbers:

Casting:

https://imgur.com/pZwPS3Q

Date code:

https://imgur.com/mRkeonH

I can't get a good picture of the block date code, but looks to be A30X. Having a hard time distinquishing the last digit, it's not cast very well, looks like a big blob, could be a 2.

In the past have verified the block casting as 481988, but I don't have a picture, next time I jack up the car I'll try to get a pic.

When the prev owner had the engine rebuilt, he had #62 heads installed. I have the original 7K3 heads, will have to dig them out and get the casting numbers.

Bottom line is, how does all this effect value? I'm not sure a 72 GTO with a 250 HP 400 and a TH400 is a high dollar car anyways? It seems like it has the born with engine, and likely the born with rear end, but not the original trans, so not sure what to make of all this.


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## etd66ss (Aug 19, 2018)

On another Pontiac forum, I'm being told the partial VIN stamping on the block is a blatant failed re-stamping attempt by a scammer. Anyone else have any pictures of their 72 GTO block stamping?


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## Shake-N-Bake (Jun 16, 2015)

I think YS is a 2 barrel single exhaust engine and YT would be 4 barrel dual exhaust. Were GTO buyers still able to select a 2 barrel engine in 72? 

The VIN stamp on the block does not look valid. Incorrect format and font.

You mention the engine has been rebuilt. Perhaps they found a suitable donor engine from a 2 barrel model and tried to transfer the VIN stamp?

Sent from my SM-G930V using Tapatalk


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## etd66ss (Aug 19, 2018)

Shake-N-Bake said:


> I think YS is a 2 barrel single exhaust engine and YT would be 4 barrel dual exhaust. Were GTO buyers still able to select a 2 barrel engine in 72?
> 
> The VIN stamp on the block does not look valid. Incorrect format and font.
> 
> ...


PHS confirmed it's not the original engine.


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## PontiacJim (Dec 29, 2012)

etd66ss said:


> OK, so here are the intake numbers:
> 
> Casting:
> 
> ...



Looking at the GTO Restoration book on the 1972, the intake is correct for 1972. 1971 has a different casting number.

The 7k3 heads are correct for 1972.

Your block's VIN may be partially hidden under the timing cover and why you only see a few of the numbers. Keep in mind that that the letter code could be a mis-strike. It is possible that someone restamped the block, but I would have thought they would have gotten it right and restamped it "YT". Pontiac has been known to do some strange things. So I would not throw the baby out with the bath water just yet.

That engine code is really needed. You should also see the 2-digit year cast on the block next to the distributor hole, such as "71" or "72" depending on when cast. This was started in 1970, so you should find that as well. It may be the block has been changed out along with the transmission. 

The trans listed for the '72 in the Restoration Guide also says "PX" is the same for 1971/1972, but it also shows where the VIN is stamped just as yours is and the VIN should be the last 8 of the car's VIN, so I would say your trans appears to have been swapped at any rate.


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## etd66ss (Aug 19, 2018)

Thanks for all your help Jim, all the guys over at PY Forums (https://forums.maxperformanceinc.com/forums/showthread.php?t=821279) believe it to be a blatant, and failed attempt at a re-stamp. I tend to agree.


I'm not too worried about it to be honest, would have been nice to be the original block, but it's not the end of the world for me. If I would have paid $10,000 more than what I did for the car, then I'd have an issue.


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## 03Marauderman (Dec 29, 2018)

I realize this is an older post and perhaps water over a damn.....Killing time on a cold winter day, I pulled out my PHS documentation for my 72 GTO 400/400. I concur with (etd66ss) that the specs he's referring to regarding his PHS docs are the same as mine...The engine ID code is 'YT' upc is'L78'. I can validate the numbers on the block on a later post, as I'm the original owner of my car and all numbers matching, with exception to the starter, (back in the day). Engine, trans, & rear has never been touched.... As a side bar, I often wondered how accurate numbers were in the manufacturing process. Engines made in one plant across the country, then shipped to assembly. End & beginning of model years, robbing Peter to pay Paul....


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