On the iso rails,----
I had a pair that the pan pads had pounded for so long, that they were deeply worn and uneven with pockets pounded in the rails.
I welded the rail pockets up, and milled them flat in the B'port making them as new.
also I bought a really nice cast iron pan on evil pray for $29 eliminating having to
Heli coil and machine the pan pads flat, to insure staying tight.
If you have everything flat they will stay tight with just lock washers and proper torque.
