An bud I know has a G8GT. He recently had a lifter failure and had it replaced with a stock G8GT cam and new lifters. Car is driving dumb. I looked at the parts numbers he had installed and they are correct for a Stock set up, but I looked at his heads and the casting is 821 (L92) heads. The previous owner has passed away, so no info on what was done. The car hesitates than goes at random times. It starts fine. Thoughts?

 

Pontiac G8 GTs come with L92 heads. Sometimes owners swap for LS3 heads. I think the 821s are LS3 heads.

 

The heads on the L76 and LS3 are the same except for the hollow stem intake valves.