Although that steel plate is a replacement, there was always a steel plate for the jump seat in the suburban. The suburban uses the same floor pan with a few modifications and with the indentation that goes under the tool box on the truck and panel, they needed the plate to be flat for the jump seat to work. As far as the location of the jump seat in conjunction with the drivers seat, they had to have a reference point for the "normal position and I think they set the jumper seat as the base. Your jumper seat looks to be in the same position as my 48.
