'68 Pontiac 400 in '84 GP

[Bender21]

I need some help with what engine and frame mounts I will need to do this swap into a GP that was originally a v6. I have heard on here that to do a 400 swap you need engine mounts from a 301 powered GP, but since this is a '68 block I thought that the mounts were different. I asked Butler performance and they said to find engine and frame mounts from an early car and possibly weld the frame mounts after the engine is sitting correctly. Do I need to find some engine and frame mounts from a '60s car then? The 400 is from a '68 Catalina. Thanks!

 

[RegalBegal]

I know later 400s had 2 sets of bosses on the block for different mounts, not sure about the earlier blocks. Either way, you could use A body (Le Mans) mounts, say 68-72.

 

[Bonnewagon]

The 68' has different mounting bosses than the 70' and later blocks. There are several companies making adapter plates to use the earlier motors in later chassis, and vice-versa. All they really are is a long steel plate with holes for the two early bolts, and welded on nuts for the later bolts. Then you can use the 301 mounts and perches, but you may still need to drill new holes in the frame cradle. GM provided holes for most ,if not all, the motors offered. I was lucky in that my 83' Bonneville had the 301 mount holes allready there in place, but you would have to test mount the block to be sure if yours has them in the right places. Here is what they look like, pretty straightforward.