If the condenser is leaking then it has to be replaced. That should have been found when they vacuum the system down, not after they put the refrigerant in.
The parts on a RV system for the Ac are not from the same vendors as cars
Look on the parts and see which vendor they used. Then all you have to do it replace not re-route . This place does many so it might be who you have. Maybe Doug might ring in and he will know for sure. If it is that old you might need to replace the flex hoses with the newer type. But you need to pull a good vacuum to check for leaks and really look over the system for other leaks before you even start.
https://www.comfortairgr.com/product-category/evans-tempcon-motorome-rv-parts/