On my 1981 Ford L8000 I have to replace the air tanks due to rust, I have sourced a couple of used tanks and wanted to restore them. I can get the outside done easily, but the inside is another question....Has anyone been through this...?

 

Fill it with pea gravel and some water and shake it around with an excavator.. dump it out, wash it out.. Maybe use some epoxy primer to help it last a bit longer??

Lots of good chemicals that eat rust.. Safety first.