https://www.hollanderparts.com/ for searching for used parts. Or try your local auto wrecker.
You might be able to get some factory parts if you visit a Dodge/Chrysler dealership, but those are likely to be expensive.
Note - Hollanderparts can also be used to show you what years of parts will fit. It also looks like the same motor and regulator were used in Dodge Ram Trucks and the Ramcharger.