When I was side mounting the maita seat in my Alfa Romeo spider. I welded plates onto the floor of car, had the seat mounts designed and on the seats , centered the seats where I liked them to be, drilled the holes,8 mm. Took it seats, and tryed to tap threads into the welded steel I added. Too far down for the tap handle to work with. So go to h.f. get a cheap set of 1/4 drive deep well scokets,and welded the taps into the sockets,,work out great.
