Suspicious "Corvette" part numbers

[G B.]

I've found two different NOS 3-4 synchronizer assemblies for sale that are both claimed to fit a '57 - '63 Corvette Borg-Warner 4-speed. The part numbers on the boxes, 3743456 and 3839383, are from GM Group 4.380.

I checked Group 4.380 in the 1958, 1966, and 1971 Chevrolet P&A Catalogs to see what was listed for the '57 - '63 Borg-Warner 3-4 synchronizer. I found two part numbers shown: in 1958 it was 3709345, and in 1966 and 1971 it was 3870789. These numbers don't match either of the two part numbers for sale.

Can someone please tell me the actual transmission application of the two part numbers for sale (3743456 and 3839383)? Borg-Warner has made a lot of transmissions. For all I know these synchronizer assemblies could fit only a 1959 GMC dump truck.

[Joe L.]

Re: Suspicious "Corvette" part numbers

Jerry-----

GM #3743456 was the original B-W T-10 1-2 synchro assembly used for 1957. It was discontinued in August, 1966 and replaced by GM #1379213. The latter part was discontinued in July, 1983 and replaced by GM #360801. That part was discontinued in April, 1987 and replaced by GM #14101337. That part has also been discontinued.

GM #3709345 was the original 3-4 synchro for B-W T-10 4 speeds. It was also used for some 3 speed applications, too. It was discontinued in May, 1964 and replaced by the GM #3839383. That part was discontinued in August, 1966 and replaced by GM #3870789. The latter part was discontinued in July, 1985.

So, the bottom line is that both parts are as-advertised. Plus, they're REAL NOS pieces.

[G B.]

Thanks for your help

Joe -

I had overlooked the 3743456 listing in the '58 P&A Catalog. It is shown there in Group 4.380, and it does say 1-2 Borg-Warner synchronizer assembly.

I could never have confirmed the 3-4 sychronizer number (3839383) on my own.

I bought the 1-2 synchronizer. Now I'll step up for the 3-4.

[Art A.]

Re: Suspicious "Corvette" part numbers

Joe, are you sure about the numbers, 1379213 and 360801 ---they just don't look right to me?

Art

[Joe L.]

Re: Suspicious "Corvette" part numbers

Art------

Yes, I agree those 2 numbers seem very "atypical". However, those were, indeed, the replacement part numbers.

[Art A.]

Re: Suspicious "Corvette" part numbers

Joe, The reason I question them, is because 1379213 is a Buick "block" number and it would be very unlikely that it was used as a Corvette Trans released part number and even though 360801 is a Chevrolet "block" number, it would also be very unusual that an earlier (6 digit) part number would be used to replace a larger (7or8 digit) part number.

Art
IthinkthereissomethingwronginDenmark

[Joe L.]

Re: Suspicious "Corvette" part numbers

Art-----

It may very well be that the GM #1379213 had Buick origins, but it was also used for Chevrolet applications. Perhaps, when the Chevrolet part was discontinued, the Buick part was sufficiently similar and functional that GMSPO catalogued it as a replacement. In any event, the GM #1379213 has applications for Buick, Chevrolet, Pontiac, and GMC truck applications.

The GM #360801 was a replacement part which originated in the mid-70s. I believe that it was a PRODUCTION part used for the 74+ style Borg-Warner T-10 (which replaced the Muncie 4-speed in 1974) which was assigned this part number for Chevrolet SERVICE part purposes and serviced earlier 57-63 T-10s as well as 74+ T-10s. There were quite a few components of the 74+ T-10 transmission that were assigned these 6 digit part numbers beginning with "3" or "4". In fact, as I recall, I thought that you were involved in the process that "reclaimed" these blocks of 6 digit part numbers for GM's use when the 7 digit part number blocks "ran out"?

[Art A.]

Re: Suspicious "Corvette" part numbers

Joe, I don't recall if Buick was the LEAD division for Design and Releasing of Transmissions in the 60's and early 70's or not, but I don't think so. I also don't think Buick released a T-10 for any of their vehicles in that time frame. Therefore, it would be very unlikely that they would Design and Release said parts.

Yes, I was the Part Number Reclamation Manager in the very early 70's and we did start to reclaim some numbers---but we only did a few hundred as I recall when we stopped. We discovered that it was going to be virtually impossible to "purge" the entire GM system of the OLD part numbers. As you can guess,for lots of reasons, we could not have a part number with two applications. Yes, this part number could have been one of the few that were purged and reassigned a new application.

The part in question would NOT have an individual PRODUCTION RELEASE application, per se', as it is part of an assembly---- only an assembly part number would be released for production.

Art