Did some research and a couple things I'd posted are incorrect. First, the transaxle is made by Dana Spicer and is a Model 012 (or just Model 12). They are very common and still in production and parts are easy to get.
Same for brakes.
The engine, a Briggs 18hp v-twin, is as common as house flies - nothing about it is hard to find or repair. The rest of the PUG is pretty simple and straightforward. The only problem we have had was NOT a broken axle but a seized bearing on the axle. The previous owner got it wet...a lot...and several of the bearings in the rear end assembly were shot. We replaced them all. All bearings are standard, off-the-shelf stuff - $10 each all day long - and easy to replace.
As near as we can tell the only potential problem with parts is the rear axles. They are $100 each and there are four and have the drive sprockets welded onto them. The axles will never wear out - they ride on bearings - but the sprockets could wear out after a couple thousand hours. Even then, it might be a relatively simple thing to cut the sprocket off and weld on a new one. So far, that is the only odd item on this machine. Everything else is pretty much "hardware store" stuff. Even control arm bushings are a commong NAPA item. Very simple, very rugged, made in USA machine. If you own a welder and a hammer, you can fix about anything on it.