[Brad54]

I rebuilt my spring bed on the full-width rear seat, and the wide part of the front bench, using a seat from a '60s pick-up truck as a donor.
If you have a welder, you can cut and weld the donor spring bed's frame to fit your benches, and fit it with the springs from the donor.
My seats had several broken springs, and a rusted out portion of the frame the springs attached to. The donor bench from a '60s truck had everything I needed.

-Brad