Yes, you will need to, engine, trans, wiring, and computer.
You will need to get a different drive shaft, for correct length.
'99 explorer will have 5R55E trans
1997 - 2009 Rangers with 4.0l also had that trans so you would need drive shaft from one of those years, 2WD and regular or super cab, which ever the '01 is.
You need to swap out the steering column for the shifter, good read here:
http://www.ranger-forums.com/engine...ing-column-w-new-clockspring-explorer-115872/
And swap clutch brake pedal assembly for just brake pedal.
If you want to keep it manual then find 1990-2012, M5OD-R1 trans from a 4.0l OHV or SOHC doesn't matter, R1HD is what was behind 4.0l SOHC but it just had an extra bolt hole.
And get flywheel for 4.0l SOHC
Check which vehicle has the better axle by looking here:
http://www.therangerstation.com/tech_library/axle_codes.shtml
get the code from the door and see what you have
You will probably want the explorer axle but you never know until you look
Both vehicles will have PATS but you should be fine as long as you have PATS keys for the Explorer computer and module, PATS module should be located above glove box in explorer, Type B PATS, '01 ranger had Type E so no module