96 t100 SQUEEKS

I just bought a super straight t100 from a grandpa and the only problem is there is a squeek neer the seatbelt in the ext cab on the passenger side like right inbetween the shoulder harness and the ext cab window. Anyone know about this? If so, how do I get to it. It looks like the panelling snaps out but the seat belt doesnt look like it just unbolts easily. Detailed help would be awesome

Has that panel been taken off? I took mine off to mount some speakers behind them and the same thing happened in the same spot. Mine turned out to be a clip on the piece that goes above the back seat pad from both sides of the truck. I had broken a tab when I put it pack on and the metal clip was rattling in the hole. Other than that try extending the seat belt and put tension on it. Sometimes the seatbelt mechanism will rattle. See if it quits when you do that. If you take that whole side panel off it is a bear to get back on so if you are not comfortable doing it, don't.