The 302 was in the explorer from 1996 to 2001
You would need the engine, computer, and complete engine/trans/drivetrain wiring harness to convert your current 96 to the explorer V8. You will also need exhaust, driveshafts, some plumbing some wiring, etc etc.......There is more to it then this, but this will get you started.
again if you use the 96-01 explorer setup you will have to remove the transmission functions from the PCM because these trucks were all automatic and the engine will not run right if the trans is not there.
Yes you could use the 90 Mustang engine, but the 96-01 explorer GT40 version of the 302 is already packaged to fit your explorer and is in my opinion a better start to a explorer conversion
Yes people here have done conversions like this many many times, the 302 has been done into all ranger based trucks since 1984 all the way up to 2011
I have done several V8 conversions myself, none using the 5 speed....yet.
Is your current truck a auto or 5 speed?