Started to assemble seats. Drilled and countersunk the slider plates per plans. When drilling on hole the clamp sliped and the hole thru the seat fram was slightly off-center. I think it will be OK as is, but lession learned. ( I used a spring clamp, should of used a C-clamp). I decided to rivet the seat-back to the frame. My plans leave it free to float, but per Rans Clan they are now rivited together. Filed the seat bottom frame smooth where it will contack the seat bottoms.