With a big Torx. The bar latch where the door connects is held on by two Torx screws. Before loosening them, make a registration mark on the top and side of the plate with a pencil or felt tip. Then loosen the screws. The plate will move horizontally and vertically (that's why you need the marks). Slide the plate in about 1/16 while keeping the side mark for vertical lined up. Snug it up and see how the door closes. Use a flashlight and look in at the door latch/plate allignment and make sure you haven't moved it so that the bar fails to center on the latch when closing or the door will ride up on the bar. You'll see what I mean. That will tighten up the door to the insulation.
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2001 HO 6 spd 2500, 4. 10 LSD, Towing Package, Electric Brakes, SPA EGT/Boost Gauges, Fog Lights, Real Backup Lights, Molded Running Boards, Lucerix X Mount Heated/Power Mirrors