can't find replacement brake pads

Hello members--- l'm new and glad to be here. l'm a regular homeowner guy with maybe an acre. But l aiways wanted a front-end loader just to help pickup things, cleanup, etc. l don't need to lift a thousand pounds capacity like a sub- compact--- nor can l afford the price tag$$$. Sooooo this past winter l found a 'nice' old( first production year) JD 400 garden tractor. l also found Little Buck Loader which is sitting on a palet out back. When l bought the tractor, l knew the brakes were 'soft' but l just figured that l would buy new ones and replace them. Guess what--- everywhere l look from Ag-Pro to garden tractor junkyards have none. Any ideas where to find them? Do brakes from a 425 or similar model fit? l live in an area where hills and inclines/ descents are common....not a good idea to carry a bucket full of anything around with insufficient brakes. Thanx for reading👍