I've got a smaller version of the same unit. (It's about 35 years old) It's 4' wide, and is self propelled. It steers with a tiller. I bought it at an auction a few years back. I TRIED to spread AG lime with it one time.
After I shoveled all the lime out of the hopper, it's been sitting since. Lime doesn't seem to flow through it like I was hoping. My intention was to use it to spread compost/lime/fertilizer on our garden. (We had a neighbor who complained to the local Polution Control District every time I started spreading ANYTHING, due to dust blowing their way. Hope was the top dresser would eliminate the dust.) (I only paid $110 for mine)
The problem with lime is it packs so tight when you get a big load. It won't feed trough the rear gate. (Known as "bridging" )
Anything short of sand needs to be extremely dry and free-flowing to work well. Pelletized lime might work, but when doing large acreage, that becomes cost prohibitive.
We're in the midst of a limestone belt here in north-central Kentucky. Quarried lime is (literally) cheaper than dirt. Pelletized lime is like gold by comparison. To do just a small lawn might be reasonable, but covering large fields with it would break the bank.
The spreader I bought was originally used on a golf course. It was used to top-dress greens (with a sand/peat moss/fertilizer mix refered to as "engineered dirt". They replaced mine with a unit identical to yours. Since then, the "new one" was replaced with a unit that mounts on the back of a Cushman work cart.
Here's a suggestion. With the ever-increasing popularity of golf, more people than ever are building practice greens in their yards. If you have any "golfing buddies", let the word out that you have the top dresser. You might pick up a few side jobs top dressing some of the home greens. Like a boat or a swimming pool, golf related "stuff" is automatic $$$$$$$$.