Matt,
I a'm here, thanks for the link. Rep sent.
The 50 on my bench is a 45 mm bore, s/n 0311318, black tag. Not sure what year that would be.
The bottom of the cylinder on this one, and a 1999 55 measure 49.96 mm, so pretty close to the service bulletin.
Good info, I will track this as I get ready to pull the trigger on my project. It seems this series of saws is worth the effort even though some look down on anything not a "pro" saw.
Definately worth rebuilding especially for general fire wood cutting and property maint'. Metal crankcase lasts and lasts and is rebuildable. Many parts interchange with Husqvarna 51 and 55 so lots of parts available. Most professionals may prefer a more powerful saw but hard to beat for the average guy.