The caps for the Federal Pumps are tough to find. They were not sold separately by Chrysler. I got one from Firm Feel when I ordered my Stage II gear. You may have to make a gasket and experiment.
Not as hard to find as you may think.
I just sold one over on ebay last week, and there are currently a few more for sale, by other sellers. mopar federal power steering pump | eBay
The op might want to check it out, if he want's to go that route.
