What would it take then?

 

I couldn't honestly say without having done it myself. The transaxle/engine combo is, i imagine, too wide. So swapping a 4l60 onto the L67 would seemingly be the only way to go, rwd wise. However, again, not having done such a thing personally, the bell housing bolt holes may be different for all I know. With that much involved one would lean toward doing a less invasive(still costly) LSx swap instead.

 

I tend to agree the 4t65e from the Grand Prix is too big to put in the lil HHR. The L67 (supercharged 3800) is pretty tall and it would definitely throw the balance of the car more front heavy than anything.

I was thinking of a 3500 from a G6 would be cool and still efficient.