LMAO, own thread huh? What's the matter TC, no one chiming in on this?
just kidding.
I'd paint them inside and out with weldable primer, clean the areas where they are going to bare metal, use the weldable primer there as well, position the rail in place and check for alignment and fit, trim as necessary, mark where they are going to be welded and buff to bare metal again on both the car and the rail. (makes for a better weld). If they are not sealed, you may want to drill a drain hole in the lowest point on them too just so moisture won't get in there and sit and cook. As far as the brake cable goes, just need to see where the best route is for it, my rails aren't welded to the floor so it actually fit over it. That's easy now isn't it? LOL, sounds easy but it'll be a job but pretty satisfying when you're done!
