the husky 2100/2101 is basicly the same saw.
it ran from 1976-1990.
there were alot of little changes along the way, but nothing major.
the bore/stroke remained the same through out.
it looks like chain brakes werent available until 1979 and these, along with the non chain brake clutch covers had small changes along the way, for example there is a different chain brake handle to work with the full wrap handle.
the second muffler option came along about 1979, this is a bigger port muffler, mounted on the front lower part of the muffler cover.
the extra rubber anti vibe, that mounts from the crank case to the felling dog was added in about 1980, and latter became a spring type(like on husky 288's) in 1987, which was when they started calling them a 2101.
in about 1983, they introduced a reinforced crankcase, which required 2 screws, that hold the 2 halves together, to be 5mm longer.
in late 1983 they introduced a new cylinder, which when mounted on an older case, requires a small post in the case to be modified. the piston with this new cylinder now has steel rings as apposed to cast iron.
this saw just evolved, as market needs dictated and problems arose. along with part numbers changing along the way, which i guess means small modifications.
the one thing im having trouble with, is identifing the thin rings and thin ring piston. im not sure how these were ordered when in the original saw, and if there is a different part number for this piston/ring????
i had a quick look at your saw and a couple of things i saw.
the recoil starter housing is off a 2100CD,
the chain brake/clutch cover is off a 2101, this type didnt show up till 1987
the wrap handle may be of a different saw???? it doesnt seem to be the correct shape for a 2100/2101.
enjoy your saw.
cheers, Serg