need help!! with engine/tranny swap

**Craig Ronshausen** · 08-10-2012

i recently got a 2000 gp gt and of course the overdrive is out, i do however have a 3800 engine and tranny in a 2005 buck lacrosse that had been rear ended, now to my quiestion.....what computer do i use if i swap the engine and tranny from the buick to the gp? i am thinking that i would use the buick computer, but idk if it would even hook up to the factory wiring in the gp...i know a lot of the parts are similar and that they used the same basic design or platform or whatever for both cars, but i would rather not have my car in the garage for a month while i figure it out, any help is appreciated, thank you

**TheOtherNick** · 08-10-2012

Pretty much your best bet is to just replace your 4th clutch hub, you need to either need to swap valve bodies, or do some wiring/pcm tuning to get that whole trans to work.

**winterstorm** · 08-10-2012

im not sure if you used the grand prix computer with the buick engine and tranny if it would just work. but i know if you use the buick computer you will have to find someone with a DHP tuner to tune that computer so the VIN matches that of your car. billboost, a member on here, has one. if you are near CT you can ask him for help, and if you arent i think he would help if you mail him the PCM

**Fivefingerdeathpunch** · 08-10-2012

To me, your best bet is to find a 98-02 trans from another GT car and swap it in. Or just replace the 4th gear hub clutch/shaft.

Anything newer cant work.

**Craig Ronshausen** · 08-13-2012

thanks guys, will a newer ( newer that 02?) clutch hub fin in the current tranny though? i have read that the 03 and up trannys have a hardend shaft so this problem is far less common in the newer trannys

**Fivefingerdeathpunch** · 08-13-2012

Yeah get the hardend 4th gear shaft.

**BillBoost37** · 08-14-2012

I forget if the 05 trans will work in this car. I think it might.

What you'd do is put your fuel rail and oil filter adapter on the buick motor, add a TB adapter to run your TB (add a port on the TB for pcv), cut the flap off the subframe if it had one to interfere with the buick's motor mount and then put your external pnp (trans) switch on the new trans. Might have to play with trans lines a little.

Overall it's relatively straight forward...then you'd use your car's original pcm and wiring harness because the engine/trans would basically be the same to your car than the original.

2007 Lucerne motor in my 2000 Regal GS

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