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97 4t65e into a 99 gtp

B

BRIAN70SS

New member
Will the 4t65e tranny out of a 97 buick lesabre work in my 99 grand prix gtp.
if so does anything need to be reprogrammed or is it plug and play. I am new to all this electronically controlled stuff. Used to the old muscle cars. Thanks Brian
 


You're going to have a gearing difference for sure, as well as as needing a new passenger side axle to fit the non-HD diff. You could run into some cooling line issues, as GM switched some time in 99, IIRC.

That's all assuming the LaSabre used the 4T65E in 97, there were still 4T60s in use at that time, and I'm not sure when the LaSabre switched.
 
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does the buick have the performance shift button on the stick? if not, you will be losing that handy feature. I'm not sure if it is the same otherwise, I was told the tranny from a n/a 3800 will not work on a s/c 3800
 
Performance shift is in the computer, so that won't be affected. The n/a trans will work fine, you just need a new passenger side axle, or swap over your original diff, housing, and output shaft. Doing that could change the gearing further, though, so you need to know what you're dealing with.
 
You need to get the ID tag info from the Buick trans to know for sure what you have and if it is compatable or not, otherwise there is no way to know what options it has and if it will be a direct swap. The cooler lines should be fine as it was the 00 model year cars that recieved the newer quick connect type fittings
 
Thanks for the replies guys. I think I will skip buying the tranny. I will keep on the lookout for one for a gtp. Thanks again Brian
 


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