I had a few of the mounting pads imbedded in the fiberglass top on my '71 K5 just spin when I went to take the bolts out,the first time I attempted to remove the top..someone before me must have torn them loose..
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I was able to get one bolt out by drilling two holes in the top and into the pad and used pop rivets to secure it from spinning,it worked well enough to carefully get one bolt to come out--the other bolt snapped off,and I had a miserable time trying to drill it out,it sheared off with a "point" and I had to dremel it flat so I could get a 1/8" bit to drill as close to center as possible..\
Rather than try re-tapping the mount pad and risking it tearing free again,or busting a tap off in it,I got a 5/16" Nut-Sert and installed that into the pad..
It worked so-so--the amount of torque required to smoosh the Nut-Sert threatened to tear the pad loose off the rivets,but I was able to get it tight enough to put a bolt loaded with never-seize to tighten in it..
I never did take the roof off again..up here the weather doesn't stay hot long enough (or dry enough) to justify the labor and hassles of removing it..
I also lived where ghetto rats roamed freely and hated having no roof on it..seemed like as soon as I got the roof off it either rained daily,or we had monsoon thunderstorms ,so that pretty much discouraged me from going topless again in it..
