Unkel Udo II wrote--" would not swear by it but I seem to remember the rear doors (outer skin, structure, etc) did not change the entire production run for 244/245. Again, fuzzy memory, but I think they may have even been the same in the 144/145."
That's correct for the 240/260 series and partially correct for the 140/160 series.
1973 is when Volvo last used the removable extruded aluminum window frame by welding the steel frames to the body and eliminating the front vent window for 1974. I've been giving some thought to installing 240 doors on my 1969 144S - the vent window has never stayed glued securely so I have it clamped shut--and the original exterior mirror is small, fragile and difficult to adjust.
The original poster should bide his time and find a door of the color he needs. A used door of the same color will have at least some natural fade while to make it look right a paint shop would have to do a "shade-in" painting the front door, part of the front fender and into the rear quarter. If his car has power windows a replacement door from an earlier model may have different connectors - not really a problem. -- Dave