First, welcome to OCC.......
Your tractor is 50+ years old. Things are going to need attention. Either from use or just sitting around. That is part of the fun (or process) of working on an older Cub Cadet.
Fortunately, parts are still available to get your tractor back in shape, Unfortunately, since the Plandemic, the prices of good used, aftermarket, and new parts have skyrocketed. You'll just have to bite the bullet on that issue.
You certainly could try using R-410A Refrigerant. Wouldn't hurt a thing, except we and the EPA don't want to hear about it. You just might have an FBI Swat Team show up at your door, at 6:00am.
