I put together a 660 also in about eight hours, starting with case halves and freeze/heat method. Every part in the Saw is from the kit, no OEM. I got the parts list from Huztl and Stihl MS 660 shop manual from eBay on CD which helped identify some of the obscure parts that nobody mentioned on any of the videos I watched. Put a Huztl 28” bar/chain on it. Runs like a demon but only near the end of my first tank of gas. Won’t use it too much, I did it primarily for the experience. like other old-timers have said, the more experience you get, the smaller your saw. I like small saws with very sharp chains.