I did mine witht the cap off. Had Ingle's Carpet in GA truck a roll over. Good price, selection, & customer service.

On my 89, The observers seat and rear corner seats were each one piece assemblies with the seat bases and backs all attached. The screws holding the seat bases to the floor were easy - just aluminim L brackets. Some of the bolts holding the seat back portions were a PITA! I think I had to go through the air vent on the port side for one in the observer's seat (or maybe through an access hole behind the port gunnel trim panel). The rear corner seat back bolts were accessed either through the speaker holes or back from the rear with the ski locker removed.