Here's the construction. I made a basket out of mild steel banding material and placed it in a 32 gallon plastic trash can.

Suspend the part from a piece of wood so it doesn't contact the sides.

Fill with water and add a tablespoon of sodium carbonate (washing soda) per gallon. Hook up the negative clip of your battery charger to the the part (cathode), and the positive to the basket (anode).

I did a test run on the battery tray. It won't be reinstalled so if I destroy it, it will not break my heart.

The bottom.

After a few hours in the tub

The bottom

After a quick wire brushing and a rinse.

The bottom

And a coat of paint just for the pictures

The bottom. Pitted but rust free.

D'oh!

The only casualty of this project was rust and my right thumb. Had a drill bit break while making the basket. I'll give you one guess where my thumb was when this happened.

This has been in my driveway all weekend de-rustificating Jeep parts.... How understanding are your neighbors? Ha ha ha ha.

The de-rustificated parts from the 1st weekend's effort. There are still plenty more where they came from.