Worked out great. Cut the torn covers off, ground the rivet heads off and drilled out the rest of the rivet, approximately 5/16 " diameter. Bought large(5/16" x 3/4") fender darts from Lowes(4 per seat bottom) and cover material from local marine upholstery shop. Re-drilled/lined up seat bottoms/installed darts before covering(Original rivets not the same position on each seat so mark individually). Using original foam, new covering material, good staple gun, and hair dryer, completed seat bottoms. Popped into place and looks better than from factory, all for $75.00, Staple gun($50) included.
KevinD