Rear seat has to come off. There's a tab where the seat cushion meets the carpet at either end. Press both tabs toward the center of the car then pull up the forward edge of the seat cushion. Pull forward then remove. There are 3 8mm head screws holding the seat back along the bottom edge. Remove the screws then pull up the seat back to disengage from the hooks near the speakers. Pull forward then remove. Peel back the black insulation pad to expose a number of holes in the bulkhead.

From the trunk, remove the lining panels. I think the side panels have to come out before the forward panel. Be careful what you do with the forward panel - that's the fuel tank on the other side.

Sixto
95 S420
87 300SDL