Re: 1982 or 1983 Moots Mountaineer
Kent Erikson (still crafting in Ti) started Moots Cycles in the late 70s. One of the first things he developed was the Moots mount which is what you see there. Basically an adjustable brake mount hat let you switch from 26-27.5-700c whenever you wanted.
The booster is also original Moots.
Kent also invented the first bar ends around 1983 (well bar middles the way he mounted them).
It looks like the hubs were replaced (with nice MN72s), RD for sure, one shifter, rear brake, and crank. Oh ... and the fork haha.