Uwe and david have both hit on it. In the 70's cabinets all had extruded aluminmum frames, and tambour doors with a plywood countertop and lightweight(thin) plywood as bottons/sides/dividers. Now the cabinets are SOLID WOOD. They are beautiful and I know many owners love them but they weigh a lot! Also in the 70's the main water tank was in the 35 gallon range with a 20 gallon black and a 0,10,15,20 gallon gray. Now the tanks are 50 gallon fresh, 25,50 gallon grey and 35,50 gallon black. Not to mention how much corian counters weigh.
In the 60's the trailers had plywood interiors, but the wood was thin and there were not that many cabinets, let alone the size tanks we have in the new ones. Fres of 20 and no gray, minimal black if even. The older ones take some additional thought for dry camping but are beautiful to see.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato