We stopped yesterday and after setting up I was cranking up my antenna when I heard this thunk on the roof. I went up to look and there are two aluminium tubing squares holding the antenna as it travels up and down held in place by a pin with a "c-clip". I had lost one of those pins and the tubing just fell on the roof when I raised the antenna. I found a real hardware store (small town, not HomeDepot) and found a c-clip and also a universal clevis pin of the same size. I bought a couple of those with hairpin type clips to keep in my emergency parts stash.
The clevis with the hairpin actually seems to be a better idea than the pins and c-clips. Just a little FYI for everyone to be aware of or add to your repair kit.
1999 Silverado LS Extended Cab, Prodigy Brake Controller