JohmM: I have a similar unit (and it's for sale too) mounted to the front of a 10 yd dump chipper trailer. I bought it with a blown engine and bad clutch. The mfg. MB (I think) is in Wisc. (I can get the number and contact if you need it). About the clutch-- like another post said--they are "pretty proud of those parts". They wanted nearly $800 for a new one and had a used one for $350. They said if I use it "a lot" to expect to replace one every year or so! Yeah, right! I spoke with a guy there who came from the original Promark and he said it would OK to omit the clutch, and use a hinged motor mount that I fabricated myself for about $50. He said the chipper isn't designed for anything over 27 hp, since 18hp was the smallest they offered for that one--so I bought a new 24hp Honda for about $1200 which was cheaper than a rebuilt or even short-block 20 hp Kohler ($1700) (I sold the wiped out Kohler for $150). I then bought a new pulley from Graingers.com to replace the clutch (be sure the new pulley and the old clutch pulley are the same dia). I had use a big, snow plow trip spring to keep tension on the engine. Runs great. I was told my unit new cost $28,000 in 1989. I have the parts book also if you part numbers.