This is a discussion on '77 to '78 Engine Swap within the Mustang II Parts forums, part of the Mustang II category; Hey all, let's say I own a '77 II (V8-302 - Auto trans) and a '78 II (I4 - Manual ...
Sure, everything from '77 is the same as '78. You'll need to swap everything, right down to the motor frame perches, transmission, driveshaft, rear end and springs. But, it will all bolt right up with no problem.