Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
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Yes, this has been covered many times in the General Discussion forum. Place your question there for a better response, but I will try to help out here.
I am not sure if the number you see is related to the vin or not. I am thinking that the number is the engine build sequence number, but not 100% sure. Pontiac did match the engine number with the vin, but not sure what year they began doing this.
The 2 digit letter codes for 1968 GTO are XM, WT, YS, WS, YZ, & for Ram Air engines XS, XP, WY, XW.
Heads for the 1968 GTO are found on the center exhaust port. Should be #16.
The factory 1968 cast iron Q-jet intake will be part #979140 or the 1968 1/2 #9794234.
To date code your block as being 1968, look at the back of the engine near the distributor for the block production number. The first letter is the month (A=Jan., B=Feb, C=March etc.), the second/third number is the day, the last number is the year -so it should most likely be an "8". New model production begins in August of the preceding year. So your block could have a "7" as the last digit if it was made in Aug=H,Sept=I,Oct=J etc. which makes it an early production model.
If the block is a late 1969 or later block, it has the cubic inch size cast on it between the first freeze plug on the side of the block. The 1968 block should not have the cubic inch size on the block.
Do you know the engine to be a 400CI? Royal Pontiac in Michigan did install a factory blueprinted 428CI in 1968. The 428 can be identified by a large raised almost pyramid shaped lug at the back of the block on the right side of the distributor.
That might help some. PHS documents would be the way to go as they give many details of your cars build and options from the factory. And, post your question again in the General Discussion and you will get a few more responses.