First of all welcome to the site.
81 on up weather stripping works for your truck, Suburbans and Crew cabs have the same 4 doors. Clearance lights are wired into the headlight switch and should be hot when you pull the parking lights on. The black plug has an empty slot in it for cab clearance lights. (sorry I don't remember which one" but I removed the harness on one of my trucks to install it on another. Lastly there is a courtesy light, or should be, between the ash tray and glove box door underneath.