This question is asked quite often. The Mono will not be a straight bolt in. For the time, trouble, and expense of going through a skid transplant, I would suggest you check into a skid from Polaris, Cat, or Doo. They will be no more difficult to install than the Mono. Yammi guys have been doing a lot of these, and to the man are much happier with the new skid as compared to the old. I've been involved in many of the conversions. If you're serious about getting rid of the ProActive and you'd like a hand, holler here or shoot me a PM. Be glad to help if I can, or at the least, get you pointed in the right direction.
-Al