Do you have the motors? Most times they just need to be taken apart and cleaned or just have the brushes replaced and they'll work just fine. If you don't have them you can look on Ebay. There's usually a few used ones on there for much less. I would just make sure they are tested first. There isn't a modern replacement you can use because of the gear. You might be able to find a Lincoln or Mustang motor that's similar as long as it has the same amount of wires.