just made some brackets for my 91 to fit the rails.
i cut 2 pieces of angle iron about 20 inches long, and drilled 2 3/8" holes 18" apart on each one. that bolts to the seat. then you can cut 2 pieces of flat stock i believe about 14" long, and drill 2 holes in each 6" apart, centered. bolt the angle iron pieces to the seat, bolt the flat pieces to the rail, flip seat upside down and set rail where you want it fore to aft, and tack it in place. then unbolt it from the seat and weld it complete. presto, done.