GM Part Question

[Mark S.]

Question for Joe Lucia:

I picked up several GM items at a swap meet recently. A "Clutch & Flywheel Housing" part #3733293-X, dated B 25 57, for an automatic transmission was among them. I looked in my Chevrolet parts books under Grp. # 0.683; however, I could not locate the above part number. Any help would be appreciated. Am I looking in the wrong section?

Thanks,

Mark

[Joe L.]

Re: GM Part Question

Mark-----

You're looking in the right section. However, the part that you described by CASTING number is not necessarily the same as the PART number for the piece. Especially in the "old days", the part numbers were usually not the same as the casting numbers for pieces like these bellhousings, manual or automatic trans types. Sometimes, the casting numbers associated with a certain part number will be shown in the parts group in the P&A Catalog. Not always, though, and that's how it is for this piece. The casting number "3733293" was not even considered an "official" identification number by GM. If it had been, I could have found it. Sometimes, these bellhousing "adapters" for auto trans applications will be found in group 4.103. Not this one, though. I checked that, too.

I've looked "high-and-low for this casting number and can't find it anywhere. My strong suspicion is that this was ONE of the several casting numbers used for the 56-59 passenger and Corvette auto trans "bellhousing". I can't confirm that, but I have a strong suspcion that's what it is. The date code is consistent with that, too. It's possible, also, that this is some sort of truck piece. I don't think so, but I can't rule it out.

[Joe L.]

Addendum

Mark-----

Something that I should have mentioned is the fact that when a casting number (such as the 3733293) is not recognized by GM as an "official part identification number", there is usually a good reason for that. That reason usually is that the casting number is used for more than 1 finished part number. Consequently, the casting number cannot be related to a finished part number since it could be one of 2 or more finished part numbers.

Since we know that the casting number is not also recognized by GM as an "official part identification number", that provides us a "clue" that this casting may well have been used for more than 1 finished part number.

Regardless of the above, I still believe that one of the finished part numbers manufactured from this casting was the 56-59 Chevrolet passenger and Corvette piece. What the other uses of the casting were, I don't know.

One of the things that would have been SUPREMELY useful would have been if GM had permanently identified every part with the finished part number. This could have been something like a stamping or embossment on every part with the FINISHED PART NUMBER in a format like "part number XXXXXXX". Such a practice would have been ever so useful to folks in the field. They didn't do that, though, and nothing can change that fact. However, they've been getting better in "modern times". Many modern day parts are fully identified as to part number in some permanent or, at least, semi-permanent sort of way.

[Mark S.]

Re: Addendum

Joe:

I truly appreciate your perspective on this. I too, believe this part was probably for a 56 to 59 Corvette or passenger application. The person that I purchased it from said that it came off a 57 Chevrolet. It was painted Chevrolet orange and it had a GM1 casting on it. One last question-Does the X after the number mean something?

Thanks for all your help! I have all the parts books from 53 to the 70's; and I just couldn't find this one. The early parts books will give you the part number and a casting number many times; however, this one stumped me.

Sincerely,

Mark

[Jack H.]

Re: Addendum

The 'GM1' emboss is usually a form of traceability back to the plant & mold that produced the casting. Most cast parts, when first released to production, bore an 'X' identifier that some say means 'experimental' indicating the part is making its maiden voyage through the production process. Such marks can persist for quite some time before the 'X' is removed from the casting process....

[Joe L.]

Re: Addendum

Mark-----

My recollection is that the "X" suffix refers to some kind of a modification from the original casting number specs. Mark Gorney might be able to give a more definitve answer.

[Mark S.]

Re: Addendum

Thank you very much for all the help!