Good day,
A 1971 M35 would have had the M36 series Ring Mount, TACOM directed 1 Apr 1987 the M36 series was to be replaced by the M66 Ring Mount. The M36 was a single ring with a skate type and not a full rotating ring like the M66. The M66 is heavy and does require the Support Kit, even if your not shooting from it. I have an M35 that I installed an M66 Ring on years ago without the support kit, the cab has small cracks on the upper part of the cab. I just recently installed the support mount kit, I found them in the classified on this site new in the box. Good price but pricy shipping. If you find the correct kit, be sure you have a good pull rivet gun, unless you have some strong hands, those 90 some rivets will kick your axx. Also the TACOM drawings that come with the kits suck. Even enlarging the drawings you cannot see the small print. If I can be of help let me know.
Regards
