MG Car Repair: seat rails in floor pans, rear bulkhead, captive nuts

Question
i have a 1975 mgb and i nead to know the measurement for location of nuts that secure the seat rails. the pans are from moss.

Answer
Hi Buzz.  The front captive nuts are exactly in the middle of the front chassis cross-member, so they must be attached to the new floor pan before it is welded into place.  Or, you could drill the holes later and use 6mm Riv-Nuts.   

The two seat runners are both parallel to the inside edge of the door sill.
The holes for the outer runner are 2.5 inches from the door sill.
The holes for the inner runner are 15 inches from the door sill.
The inner runner rear hole is 9 inches forward of the rear bulkhead.
The two holes in each runner are approximately 14.5 inches apart, but use a runner as a drilling guide.
If you mark the holes out before drilling, you can check that you have got it right.  
The front holes should be inside the front chassis cross-member, evenly spaced front and back.