Also, check out the range of travel of the pto driveline when mounted on your tractor.
If the driveline was properly fitted for the bush hog for use on a tractor noticeably larger or smaller than your tractor, you might damage your tractor or the bush hog, or the inner pto shaft might slip out of the outer sleeeve and go banging around!
The are multiple sources on the internet showing how to properly shorten or lengthen a pto shaft.
