Thread: Trans compatibility '06 vs '07 Grand Prix GT

Hi all,

long time lurker, first post! This place has been a great resource for wrenching on my (wife's) GT so first off, THANK YOU.

Here is my problem: my wife's car developed a bad misfire at 165k miles. While I was trying to track down the problem it showed itself with a loud "crunch" from within. It dropped a valve. So I assume I had a broken valve spring that I didn't find soon enough which lead to dropped valve. The engine is toast. Yesterday I located and purchased a low mileage engine and transmission from a 2007 GT. My wife's is a 2006 GT. I'd prefer to swap both engine & transmission due to the lower mileage.

So my question is: what are the chances of the '06 and '07 transmissions being 100% interchangeable? I understand internal components may change from year to year so I'm hoping somebody else has done this and/or might be able to offer some confidence that if I replace her '06 transmission with the '07 that I'm not going to run into problems.

Your help is much appreciated!

Thank you,
Nick

would the heads still be usable if the spring broke and the valve caused some damage?

WOW! Thanks for the quick reply!

Yes, both are Supercharged. That's great news. I figured that the supercharger and manifold might have some value but I hadn't looked into it much. The front head should also be in decent shape. Even the original 165K trans has been just fine but I figured while I'm in there I should just swap in the low mileage trans. Is a 165k mile trans worth anything? I may just slide that under the workbench until we sell the car.

SGTMarshal,
The engine in her car does run but the sounds it makes are pretty terrible. I shut it down before more damage occurred. I pulled the rear valve cover and one exhaust valve is missing...yes MISSING. I'm sure that portion of the head is pretty beat up but will definitely be pulling the head off to take a look once the engine is out.

Thanks again guys,
Nick