The rusted parts are ones that spin and can't or shouldn't be sprayed with rust protection. The drive shaft, transaxle, and, adjusting weights for the levelling. The only other is exhaust, in mine is stainless steel.
Any other parts on mine don't have rust because I had a rust protectant sprayed the first day before I took possession, but, if you don't spray then other parts will begin to rust very quickly in high salt areas, specially if you drive in snowy areas.