1996 explorer would have the 4.0l OHV engine, same 4.0l engine as in a 1990 Ranger.
1997 explorer could have either 4.0l OHV or 4.0l SOHC, these are totally different engines.
So assuming it is a 1996 4.0l OHV engine it would use same fuel pressure as 1990 Ranger.
2WD and 4WD engines do have different oil pans, for front axle clearance.
The crankshaft from 1990 to 1996 had 6 bolts for flex plate, in 1997 it had 8 bolts, so assuming 1996 you should be fine.
1990 4.0l ranger would have an A4LD automatic with TCC and OD computer controlled solenoids
1996 4.0l explorer would have 4R55E automatic with full shift control solenoids
So your 1990 computer can't control the 1996 transmission, can't use it, it also doesn't have speedometer cable hook up
Rangers didn't get 4R55E until 1995, when the newer EEC-V computer was added with OBD2, probably not a road you want to go down, full wiring change needed.
Sell the 4R55E and used money to rebuild A4LD if it needs it.
You would pull the lower and upper intake from the 1990 4.0l, and use it on the 1996 4.0l OHV, that's to match wiring harness, and no benefit in using the 1996 intake in any case.
And yes swap the oil pan, also replace rear main seal, they are cheap and hard to get to with engine installed.
The 1996 will have a Cam Synchro behind lower intake, 1990 will have a "plug", you need to swap the "plug" to the 1996, that is the oil pump drive, important part, the Cam Synchros had bushing issues, they wore out, while you could leave it in, it is just easier to swap out with engines out of vehicle
Basically you just want the block and heads
Here is an article on the 4.0l OHV: Rebuilding The Ford 4.0L Pushrod V6, Doug Anderson, Automotive Rebuilder, April 2001