To answer your question, the answer is no.
Its not that the PCM itself would not work but if you were to take the PCM out of the 02, the programming will be completely different.
Basically, the way these computers come is as a completely blank unit. Once installed into the vehicle, all of the needed information is down loaded into the programming scan tool and then loaded into the control module.
At that point, all of the information needs to then be loaded into the computer from the body control module, anti-theft module, climate control module ect.
The only way to replace a PCM on your Buick is with a new unit and then having all of the needed information downloaded..
Please let me know if there is anything else that I can assist with...
There is no need to replace any gaskets unless that you are aware of a leaking problem. If everything is dry, leave it alone.
Do lube up the axle seals with WD-40 or trans fluid before you put the axles in...