What problems will I have will I have to get new motor mounts ,will it bolt up to 4 speed transmission. Its a 77 f150 custom. It had a 400m in it

 

The 400M to 460 swap should be pretty painless. The 400M is essentially a larger 351M and there have been numerous 351M to 460 swaps done. You will need different motor mounts and depending on the year of the 460 you might need a flywheel for your 460 and possibly a different pilot bearing. The bellhousing is the same so if you have a later 460 you should be able to bolt up after you get different motor mounts.

 

Thanks