# TH400 Identification help



## NC70GoatMan (Mar 23, 2011)

My '70 GTO Convertible lost the engine and trans way before I took possession of the car and was able to source another YS400 with 13heads (Auto) pretty close to build date. The trans, however, was once in a '77 Oldsmobile. It was professionally rebuilt and works great but was wondering if I can get some help deciphering the Olds application. The ID plate shows: *77-OB-75218. 
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Thanks in advance!!


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## O52 (Jan 27, 2019)

From an Olds website.

On the RH side of the transmission, just above the pan, is an *ID plate*, about ½" in size. Gently wash off the grunge and look for the ID code painted on and stamped in as well.

It'll be of the form "OA-##-1234" where the 1st letter tells the car make: O is for Oldsmobile, B is for Buick, P is for Pontiac, etc., and the second letter denotes the application. Generally speaking, the higher the letter, the better. Some will have three letter designations, and the first letter can vary, such as L or J or F, etc.

The ## numbers is the year of the car: 68=1968, etc. No mystery here. The last 4 digits [1234 above] are the transmission unit number, not unlike the engine unit number found on the oil fill tube of 68-up engines.

Also, for 1968 and up applications, the VIN derivative will be stamped into the LH side of the transmission, between the two ribs and just above the pan. This will be the same number/letter combination that the engine received- see engine ID above for particulars.

*[ Thanks to Graham Stewart, John Pajak, Mike Rothe, Greg Beaulieu, Bob Barry, Bob Handren, Jim Chermack for this information ]



From what I gathered in a few minutes of looking, the 'B' code was for the full size cars. If you check the VIN on the drivers side of the case just above the oil pan it should give a clue as to what car it came out of*


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## NC70GoatMan (Mar 23, 2011)

Thanks for the reply. I'll try to get the trans VIN next time I'm under there. Just wondering what donor car the trans came from. I was hoping a forum member may have an Olds manual with the info.


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