Unfortunately, replacement parts infrastructure for anything other than car parts, is NEVER as good as automotive. I suppose it must be because automotive is really the only parts industry that has massive amounts of aftermarket manufacturers and retailers. Typically with anything non-automotive, your only choice is OEM, and you have to buy it through their own people and dealers. Even IF there's an aftermarket option available, it's usually only for consumable parts like belts and bags, and they always use the manufacturers' part numbers. And to top it off, they don't like to give out information like parts lists, diagrams, etc. Sure, they are 'available' but not on the same accessibility scale as automotive, where literally anyone or their dog knows the part number of an oil filter for a 1994 Chrysler LeBaron, and can offer you TEN different options to choose from.
Add to that, that most generic parts, like belts and tires, have their own standardized system of part numbering. If I want a P225/60R16, it doesn't matter where I get it, it'll fit anywhere it's meant to, and I can have it in 20 different flavors.
