One other thing to check (probably after you purchase it) is the PTO length. I'm not sure there is a standard length among CUTs.
Pretty easy to check: pull the shaft apart, hook the tiller to the tractor. put the PTO on the tractor. Now hold the PTO shaft side by side. At full up, you don't want it bottoming out. At full down (might want to put your tractor on a 6" high stack of wood to approximate tilling depth), the shafts should overlap several inches.
If it bottoms out, or comes apart, you can replace parts of the shaft and shields, or buy a whole pto shaft assembly and start over.
ron
!. Category 1 attachments will fit most if not all Category 1 3 point hitch setups regardless of brand tractor. The categories are standardized. I agree with Ductape- you want to overlap/offset at least one of your rear tires. You really want a tiller that is wider than your tire width. You should also look at your PTO HP and the power requirements of the tiller, but that is subjective based on soil and intended use, but a 7800 should run a 50'''er. The HP requirements of the tiller are usually based on the strength of the gearbox. You really do not want to overpower the tiller. Most tractor PTO's will drive a tiller, but how well can be an issue. You also need to be concerned about the tiller's weight. Some tractor's 3PH are not capable of lifting the "monster" tillers that are out here in the marketplace. You also need to be concerned about balancing the setup- you do not want your front end up in the air while tilling. Having rambled on like I have; I think the 7800 should handle it without much problem. Jay