I wasn't sure which category to put this in, Admin go for it.
I found this out the hard way. The top shock mount on the rear of my 2005/4 Chevy Express based Roadtrek MH uses 2 threaded spring clip nuts to attach the 2 bolts on both sides. On both, I had one bolt that would not unscrew until the other bolt was removed and I pulled down on the shock as I turned the bolt. I assume the factory installer over tightened the bolt. OK, no big deal maybe 30 cents a nut, I just replace all 4. Uh huh, Chevy stealership wanted $4. apiece, and the kicker is, they are not available anywhere in the US except in Lansing MI. Special order only, several days at least. Yes, similar nuts can be had locally, but they don't have the width of the OE nuts and the holes they go over are large enough I didn't want to risk them pulling through. So I ordered them.
If you are going to replace the shocks on yours, look to see if they use these crappy nuts. Then order them before you start or you may be like me. Waiting.
Fortunately, on mine, the front bolts screw into the frame, not these silly nuts.