Are you just replacing the headlamp or the complete housing?
If you're replacing the housing, most likely you'll have to remove one of the headlights to get the number off the back. At least that's what I had to do. While mine were Dodge Ram headlights, they were made by TYC who stamps the number on the back. The taillights are Lincoln Navigator but again, the number was stamped on the back by a different mfg. AMC or something like that, I don't remember. Point is, remove one and take it with you.
If simply replacing the headlamp, take one out and match it up. There should be a DOT number you can cross reference too...IIRC those headlamps are oversized anyway, so they may be harder to find, but someone has them...google may be your new friend here......Dennis