My mod. My old "C" springs were very close to bottoming out, so something had to be done.
These coil springs do the job. Also when I moved the seat back for the belly room,
I put a piece of about 12x12x1/8" steel on the underneath side of the fenderdeck for extra strength.
So far no more cracking around the holes where the seat fastens.
The seat is bolted solid and has no fore & aft adjustment.