what needs changed to put explorer motor in 95 stang?

Just drop it in there. Make sure you use the intake from your 95 mustang there. Its the same motor except for heads and cam.

You can use the Explorer intake, but you either need to do the swap to the Fox style throttle body, or pick up an elbow. You should swap in a different cam while you're at it (not necessary, but the Explorer cam isn't very performance oriented), as well as use your 95 distributor, oil pan, valve covers, and all the accessories from the Mustang.