tranny mount problem

[71MUTT]

Well, I need to say that I am a terrible mechanic. I can do the basics on my truck and have for years, like starters, water pumps, fuel pumps, alternaters, points and plugs, carrier bearings, universals ect... Done all these multiple times on me 71 C-10 LWB. Never pulled an engine or tranny before.

Lately I've been feeling a shimmy or vibration on low speed acceleration. So I'm under the truck looking around and I see that the tranny mount bolt is loose. So I tighten it, go to the otherside to tighten that one and it's missing. So I match up the bolts, spend a hour trying to line up the hole, then finally get it started. Tighten it. Tighten the existing one. Go back to give the one that was missing one extra pull and.....................stripped. Dam, was I pissed. Here a pic of the bolt. What did I ruin in the tranny and what should I do. Just having the one bolt tight seems to have solved the problem, but would like to have both bolts. Sorry about all the dirt and grime. This tranny has 250,000 miles on it and has never been worked on. (Or cleaned )