The problem I am having is , someone drilled 5/16 hole in the subframe and crosswise channels and had bolted the seat riser in place. Yesterday I looked at another coupe and the rivets looked like floor pan rivets. Maybe I'll have to weld up the hole's and redrill to 3/16. I didn't get a chance to look under the car. Are the original rivets 3/16? Thanks for the reply.