Removing brushed on RUST-OLEUM from axle housing?

Honestly this IMO is an instance of "do it once and do it right". If you take it down to metal using power tools, what's your plan on recoating? Most likely a rattle can, right? Maybe you will actually paint it, I don't know.. I've painted them before, truly it's a waste.

The most lasting way, and the cheapest way is powdercoating. Lasts forever, looks perfect.