The oiler worm gear on my 61 got chewed up. Every oiler gear I’ve ordered is too small, the gear teeth don’t even touch the oil pump gear. Are there different sizes of worm gear for that saw?I have a 61 white-top that I saved from the dump years ago. I used a starter cover and chain brake from a 272, and don't recall any problems with fitment around the muffler.
I just finished rebuilding it this year, and there are some differences between it and newer huskys:
-air intake, air filter and top cover. Already been covered.
-clutch. The older 61s use a large coarse thread on the clutches, while newer one use a 10mm fine left hand thread. The older style of clutch is getting hard to find, so keep an eye on its condition. To upgrade, you need to change out the crank.
-muffler bolts. Originals used 5mm studs, while later ones are 6mm. I simply drilled out the muffler to get 6mmx90mm bolts to fit.