This is what i found:
The rear axle spring perch spacing (center-to-center) for a 1972 Dodge D100 (2WD) is approximately
43 to 43.25 inches.
Key 1972 D100 Rear Axle Details:
Perch Spacing: ~43.25" center-to-center.
Axle Type: Commonly equipped with the Chrysler 8.75" rear differential, which...
11 No ignition reference signal detected during cranking (bad Hall effect) OR timing belt skipped one or more teeth; OR loss of either camshaft or crankshaft position sensor. Can cause the engine to stop working entirely with no limp-home mode.
12 Battery or computer recently disconnected
13*...