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Thanks. Is this the case even if it is not the original block from the car. Also why the xw?
I believe the 64 block had an engine unit (identification) number that was different from the VIN. So "numbers matching" really isn't for the early GTOs. And the W code = 4 speed, X means both automatic and manual flywheels can be mounted.
 

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Numbers matching IS for the early GTO's. The Engine Unit Number, listed on the factory Protect-O-Plate, I.D's the engine to the car. VIN numbers did not appear on GTO engines until the '68 model year, and were different from the EUN. Agree that the 76XW is a real rarity these days.
 

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From my understanding the code 76 alone tells you it is a 1964 389 cid 348hp tri-power with a manual transmission. The X stamped tells you that the car was for the standard manual transmission. The standard 64 GTO came with a 3 speed manual. If you optioned for the 4 speed wide ratio that is where the W stamp came in. The code number 8 was stamped on the block if the engine was matched to the 4 speed close ratio trans which was offered later in the 64 model year. So 76XW is the optional 4 speed wide ratio 389 tri power.
 

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Discussion Starter #13
The PHS paperwork simply has 76 for engine and W for transmission. Would the original order form have said 76xw or just w?
 

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1964 is an odd year for engine codes. Paperwork wise (passenger broadcast sheet and PHS) will just have numbers to show what kind of engine you have. 76 like your asking about is the 64 389 tri pwr with manual trans rated at 348hp. For some reason someone in the plant stamped letters on the block to make it easy to determine where that engine is destined to go such as the letter X for manual transmission cars. Later down the road another letter was stamped to show what kind of manual trans it was to be mated with on the engine. That is why you see the one picture i posted a few post back of the W being way off to the side.

65's WS tri-pwr engine codes does not tell me if the car came with a 4 speed or a 3 speed, just a manual transmission. Your 1964 76XW tells you everything about that engine.

So 76 is all you need on the block but the plant gave you some more info by the extra stampings.
 

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Discussion Starter #18
Last question on this topic. Is there any other way to correlate an original block with the phs paperwork? Some other code or number? Try to understand a claim of authenticity.


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On '64-'66, no. Only the Protect-O-Plate will bear the original EUN. (Engine Unit Number). The PHS will just have the letter code, but not the EUN that came with that particular car.
 
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