Alright, so I'm having some trouble.

I've got this set of wheels, Raceface Aeffect 27.5s. It's the previous style of hub they were using before they started using the Trace hub. The rear wheel currently has an XD driver on it, but I want to switch to a shimano freehub body. Apparently that's a tall order, as I am having a terrible time finding the freehub anywhere. I believe the wheels are 2015, so they shouldn't be old enough to not have replacement parts still available.

Here's where things get weird. Based on what research I could find, I need the freehub that it is stamped with FH-502. Does anybody know what that necessarily means? To my knowledge, there's no standard for freehub sizing or anything, and in 5 years in the bike industry, I've always heard that you have to get the same brand freehub body as the hub. And yet, a quick google search of "FH-502" will bring up a ton of Cannondale and Crank Brothers freehub bodies. Would these in fact be compatible? Is there some sort of standard which labels some freehub bodies the same if they are cross compatible. The only other lead I have is that there's a chance that all freehubs marked with "FH-???" may be Formula brand. But it seems strange that raceface would've just rebranded a bunch of formula hubs for their wheels.

Anyways, I'm very confused. Where can I find the correct shimano freehub body?