I haven't had a chance to get out to the conversion location to measure the exact size of the rivets, but they are the biggest I have personally seen.
I'll be the first to admit that I don't know all that much about the different types of rivets, but I believe they are blind rivets and definitely made of steel. I know there is a distinction between open and closed, but I don't know what that is in practice or just to look at...
I haven't tried grinding because the bottom rail is deep and not very open because of the lip used to secure bolt heads for the actual seats, so I'd have to cut away pieces of the rail to be able to get any type of angle at all. I could grind the top, but I'm looking for a solution that I can just use on all of them.
Thanks for all of the suggestions, I'll try them out when I get over there next (possibly tonight, though the weather is terrible here today).
Anyone ever try this out?
I stumbled across this and am thinking it may work well on the bottom since I could get the blade straight in and not have to worry about any angles.