I love my 066... I did get diffy bars for it though as it was not necessary to take to most jobs with a 36 bar. I bought first a 25 bar for the saw ( I have a tendency to size down bars with in reason) MAN you talk about a cuttin fool... BE SAFE here applies. Now this saw makes some money as it bucks like a raped ape.. Does with the 36 also, but you don't have too much bar stickin out of the log or when you fall less flex in the bar for good straight kerf. In these mountains, we have rocks, better with less bar hangin out the other side if the wood if ya follow me. I recently traded some work out for an 036 with a 28 inch bar. Low and behold.... The 25, 28, and 36 all interchange between saws. So I now have 3 bars for my 066. Chain size is the issue for the 28. Drive link amount in position to sprocket and bar length. 25 chain and bar fit both. Aint gonna run 36 on 036, that would just be silly, it will easily run the 28. I used to have take the 066 sometimes on the big pines, OUCH. I weigh 140 lbs, can we say boat anchor! Now the 036 works in the tree much better when I need the bigger cut up high. I primarily run the 036 with the 25 now, the 066 with the 28 and 36. It earns its keep now. And at the price of the 660, rebuild seems more practical than replace , plus the kits out now, parts accessable. Diversify my friend, diversify, and you can speed up your cutting and get it done.