I bought an 1100 a few months ago. It came with a Continental KTR 48 inch belly mower. Continental is now Ag-Meier, they still sell this mower (called a Thoroughbred model) and SSB Tractor has them on-line. This mower is built well and cuts well and the company was very helpful when I talked to them on the phone.
However, there is one major problem. Mounted on the tractor, the mower doesn't have much ground clearance at all. This isn't a 3 pt hitch adjustment issue...measure the distance from lowest spots of the belly of the tractor to the ground (sitting on a level concrete surface) then measure the height of the mower deck by itself...there's only about 2 and a half inches of difference, for this mower and my tractor. The parking brake lever will hit the mower deck if the mower deck is raised any further. (if you remove the lever, then you gain about another quarter inch or so before the deck hits the hydraulic lines and other stuff on the tractor belly). Now, I'm not mowing pasture, but my yard isn't a golf course either, so 2.5 inches ground clearance isn't acceptable to me. In fact, I'm considering doing some major modifications to this mower deck, to make it a rear-mount mower rather than a belly mower.
I hate to modify the mower but it kinda defeats the purpose of having a tractor. But if you live near Nashville, and would be interested in a decent used belly mower (knowing its limitations), perhaps we could work something out....although then I'd have to shell out for a rear finishing mower....