In our '74 Ambassador, the wall panels are a thin luan plywood sandwiched between plastic laminate sheets on each side. Some of the cabinets are luan with one side plastic laminate and one side of the plywood just painted. In the bathroom, there is white plastic lam on one side and the dark walnut laminate on the other.
It takes thorough prep work and the right materials to paint over the plastic laminate, or you can put a different plastic laminate on top of the old. If you put a new laminate over the old, you need to really clean up the old stuff and "scuff" it with sandpaper so the adhesive can really grab it.
If you have any questions, please let me know, I am about 2/3 of the way through a renovation of ours. We are planning a trip to Oklahoma in May, and will likely be staying at the Choctaw KOA.
Laird and Nancy