seat attach blocks, I modified them
 

87 911, interior upgrade. I had my seats out to replace carpet, install rumble Matt. After completing upgrades, it was time to re-install seats. PITA, trying to hold seat in position while holding attach blocks in place is-difficult! So here's my solution: I bolted attach blocks in place, drilled seat rail & blocks. Then taped (8/32) block. Drilled counter sunk hole in seat rail, then installed attach block to seat rail with 8/32 counter sunk screw. After each attach was drilled/ taped & installed, place seat on rails and secured seat to attach blocks. Pics to follow.
Terry

Strange I never had that problem. The seat is flat on the rails and I just have to thread the bolts in. There is enough room under the seat rails for me to hold the blocks.