The King Kutter XB Series units use the same pto shaft with slip clutch as the KK II 4,5, and 6ft units. The KK 7Ft. unit is the only unit that uses a different size larger PTO shaft. I have never had that kind of feedback from any customers.I was looking at a king kutter II 48" tiller that is on craigslist locally for $1100. My question is, Its going on my 2305(18 pto horse). Tsc says they are rated from 20-35 hp, but I am not sure if that is pto hp or engine hp. My local tsc store recommended the 48'' xb because they have seen the kk II break pto shafts on smaller tractors. Jd's tiller is 47'' and they say the 55'' will work also, so I was wondering why the kk II wouldn't work. Am I missing something here? Any thoughts or recommendations or opinions would be greatly appreciated.