I’d almost forgotten these D-Series medium duty trucks existed; they were always a quite rare sight even in their day. The fact that they were built for only four years is part of the reason; Dodge didn’t switch their medium duty trucks to the new D-Series cab until 1974, two years after it first appeared on pickups and light duty trucks.
Dodge exited the HD truck market after the 1975 MY, but kept the mediums going for two more years, through 1977. But they continued to be built in Mexico for a number of years yet, well into the 1990’s.
Here’s a small sampling:
Seems that these were perhaps more common as farm trucks/grain haulers than in any other use, as there’s a few still out there, including this immaculate survivor from Canada, a 1975 D600.
The original build sheet is still with it, and that says that it was powered by the 318-3 V8 (“3” being a heavy duty version), backed by a NP435 4-speed. That’s a pretty modest power train, but grain haulers didn’t really need more, in order to fulfill their mission to getting the grain to the nearest elevator. It does appear to have a two speed rear axle.
Here’s another farm truck survivor. Farm trucks do tend to have a high survival rate and long useful life, given how infrequently they get used. There’s a farm nearby here that still has a row of four International trucks dating to the late ’40s or early ’50s sitting in the shed, used annually for their mint crop.
A fair number also were used by school bus manufacturers.
Engine choices for all four years were a mix of V8s: the 318-3 was std. in the D500, D600 and W600 (4×4). The 360-3 was optional on these and std in the W400 and D700. The older 361 V8 was std in the D800, and the venerable 413 V8 was optional on the D700 and D800.