OK. ALL aftermarket tails i've delt with, the inside screw holes(drop tailgate) have always been off from what was on the truck. Just drive some screws in there....and it'll work just fine. The APC tails on my little bro's truck were like that too....i drove the screws in and 4 years later, the tails are still on the truck. All the screw holes punched into the bed are in the same location no matter what year truck. all tails are interchangable. If you want it perfect, should've bought OEM FORD ones.
'99 and older rangers are 3 bulb taillamps. '00 and up are 2 bulb taillamps. MANY MANY people have converted to newer 2 bulb lamps....There's many threads talking about it.
You can splice off your trailer harness. You can eliminate the back up lamp, and just run the signal bulb in that socket w/ an amber bulb or red bulb. There's other ways to do it too....to convert to a 2bulb lamp.
'01 XLT disguised as a '03 Fx4 Level II
Big. Loud. Slow. Bright.