I have a '66 C-10 with coil rear springs. It doesn't have the optional leaf overload springs' and I found the springs, upper, and lower brackets at a local salvage yard that specializes in vehicles from the 30's to the 70's. I was wondering which holes in the frame behind the rear axle are used to line up the upper bracket because the four holes in a line are not there. There is a hole in the bottom of the frame and one on the side that looks like they might be the one or two used to line up the upper bracket. Any help is much appreciated.