Ductless? Doesn’t that mean free of duct tape repairs? :P
You still need duct tape in an old RV even without any ducts. The GMC is much better about it than most other 70’s models due to it’s fuselage style construction, but old exterior seals and gaskets spring leaks often enough that a stop-gap measure is necessary until you can get up there and reseal with something a little more permanent or completely replace the gasket.