We have converted the 40 inch Bercomac lawn/garden tractor soft sided cabs to fit on the R series Montana and the 10/20 series Branson compact tractors. You can see pictures of the converted units on our company website rhfinc.webs.com under the Berco cab directory.
We reworked the rear bracket mounts to weld angle irons on the bottom to bolt to the fenders. Normally, they are bolted on the rear hitch of the lawn/garden tractors. This will be the third year for our Branson unit and have not had any problems.
We have a link to the Bercomac website for you to locate your nearest dealer. They also have come out with a compact tractor cab. Depending upon the size of the tractor platform, the smaller cab may fit better than the larger one.