What's the big difference between OPG's rear interior panels? There is a part# FP91300 (assembled) for $183.00 and part #DP91300 for $45.50.
What is not done on the "non-assembled" units?
Any help appreciated!! :D

I believe unassembled ones are essentially the vinyl only. You need to transfer the backing, moldings, etc. from your old ones. I've never worked with the unassembled ones, hopefully somebody can be more specific here.

MRSS,

Don is correct. You will need to transfer or install new the top metal curved panel, lock knob/button chrome ferrel, window felt and any emblems. Plan on spending the better part of a day.