My 88 cougar has a bad 3.8, and i was given a 4.0 from an explorer. I'm not sure if the motor mounts will line up. I'm still looking into it, and I was wondering if anyone here knows. I'd love to go to a 5.0 but don't have the time or the money to invest into the project. This is my daily driver and With winter coming i need to get it fixed. the 3.8 has a crack in the block, so its toast.
The 4.0 from the explorer has totally different motor mounts and bell housing than your 3.8L. I would be much easier to install a 5.0 in place of your old engine than a 4.0
I have 3.8L engine for sale if you are interested. See the link:
http://www.foxtbirdcougarforums.com/showthread.php?t=16604