Transmission questions...which trans fit which cars [Archive] - GrandAmGT.com Forum

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The Grabulator
06-08-2008, 07:49 AM
I have searched so if this is a repost I'm sorry

The transmission is going in my 99 grand am (3400). I know GM changed a lot of the electronics on these cars in 01. My question is, if I get a 4T45E from..say..an 03 grand am to replace mine, will it work? or are the electronics different?

AaronGTR
06-08-2008, 09:41 AM
They didn't change anything major in '01. No idea what you're talking about there. The 4t45e from a 2003 model will have some improved internal parts, but as far as electrical harness and operation goes it will be exactly the same as your 99, so it would actually be a very good replacement.

The only thing you'll want to check is the final drive ratio of the trans you're getting. If you check the RPO sticker under your spare tire cover, it will have "MN5" somewhere on it for the 4t45e trans. Since yours is an SE it should also have "F83" somewhere which is for the 3.05 final drive. Make sure you get a trans from a car with an F83 RPO code. If you get one from a car with "FR9" that is the GT transmission with the 3.29 ratio. You could use that as well, but you'll have to have a GT program loaded in the pcm or it won't drive right.

The Grabulator
06-08-2008, 11:05 AM
Thank you very much. This is exactly the information I needed.