The 930 absolutely never came with the 920 air filter cover. That was one of the main distinguishing features of the new models, as JJ said.
Another significant difference was the top mount going to a spring style vs. the rubber mount on the 920.
There was some overlap on the rings, but the 30's got away from the thin rings and switched to the thicker style. They bounced around a little with the rings, bot with the 920 and 930.
Cylinders were different in the later 30's as well. Early saws, and of course the 820/920 were standard closed port like a 288. Later saws had a modified closed port with the transfers open to cutouts in the case, (similar to a 372), but still ran a windowed piston. I'll post pics tomorrow. Tilton actually reworked many of the early saws here in the states before selling them by re-machining the jugs.
There were 3 muffler styles on this family of saws. Top-front exit with the louvered chrome plate holding the spark screen, top right side square hole exit, and the bottom exit with a square louvered plate similar to a 2054/5055. The last was I think unique to the 830/930 and is definitely the best of the three. Take the 4 screws out, remove the inner baffle, (part# 501486401), and you have an instant muffler mod.
Always keep in mind with older saws that what you see may have been changed over the years. Especially with this family of saws because as new parts became NLA, there was a lot of mixing and matching going on to keep them running.
