Steel parts go in a "Stripping Bath", where the current is simply reversed. The pH of the electrolyte is critical, as any alkaline solution has a tendency to dissolve aluminium. Don't clean crankcases in Caustic Soda! Stripping Chrome from Aluminium may be a bit risky, so check with your chrome plater, but don't be surprised if they decline to do it.
Any chrome plated aluminium parts I have seen, done on the cheap, have lost the chrome easily, just peeling off in strips. A proper job should have a base of copper, then nickel and finally chrome, this is not the case on cheap backdoor jobs.
Swarfy.
