thx for the input everyone--i'm not nearly the knowledgeable monty brain that the rest of you are (yet)! ... anyway, truck is at a friends place and is nearly done...it has some really ugly aftermarket wheels on it now, with some aftermarket torn to-pieces center caps. don't know what's under them--esp. the "auto locking hubs" printed centers (??) ... but am i hearing you all say that the original factory center caps may not fit my aftermarket wheels? i've got 15x7 cragar soft8 black steels, 4" backspacing. anything i should know?

91 two-tone LWB 5-speed, sunroof, third row seat, 31" wrangler authority's on black cragar soft 8's.