Chainsaw Repair

Yours is the first 550 pic I have seen with the updated 2 shoe clutch, more like the 346 clutch.  The 550 and I think 545 I had both had the early 3 show clutch.

Here are some changed parts with the old and new numbers:

Inner clutch hub  574 23 61-01    577 51 82-01

Drum  575 26 10-01  575 26 10-03

Muffler  523 05 26-01  523 05 26-02

Coil  577 79 07-01  581 72 36-01