Some of those parts will fit and some won't. Heck even some of the early 066 parts won't fit some late model 066s. The bearings should be the same though. There were two different sizes of seal on the flywheel side. I think you would want new bearings and seals anyway. Mike
I didn't know that most of the fallers here jumped from the old 051s to the 66s when they came out I never seen a 64.
Most guys don't use 051s much anymore time is money so new saws are used if you have big wood to buck the 66 or 88 gets used. When I had to get parts for my 051 I would have to wait weeks for them as the Stihl dealers had to order them its not something they stocked.