Hi I have a 1991 f-150 300 straight six 5 speed and I was wondering what v8 engine would bolt up with everything with out very much truck any help would be appreciated thanks

 

The 302 and 351 will both bolt to the trans, but not to anything else. Motor mounts and radiator need to be changed as I understand. And you'll need to get the ECM for the new engine. Swapping in a different engine is a BIG project any way you cut it.