I have a 1977 C10 that has a rear flip kit and drop spindles up front so its pretty low. I measure 6 inches in the back. It's frame isn't notched though! The guy I bought it from says he didn't have a problem and he loaded a polaris ATV in the back during the winter. Could this be? I'm thinkin he had a sound system and didn't hear it. The axle is pretty close to the frame... I have the bed off right now and am about ready to install a bolt on one but first I wanna see what you all think first.
I also wanna add that I'm not interested in the debate about weld in or bolt in kits. I as a welder do not approve on welding the frame and have done so once in my life to fix a crack and was unsuccessfull. I'm not into gambling and when you weld a spot there is a "heat affected zone" around the weld that is brittle then the weld itself is super strong. Ends up being hard spots and you want it to give..