drive shaft measurement

It is fairly easy to measure your car. It works best with two people and you have the shaft out. Car on the ground or supported( as it sits on the ground) with jacks.
Measure from the transmission spline shaft where it sticks out of the tail shaft, to the rear axle pinion flange at where the u-joint bolts to.
Then you can take that measurement to a shop or find one at a swap meet. If there is not engine/trans or rear axle you may have to wait. I have on out of a 72 Duster, but it will take me several days to get an measurement. Hope this helps, let us know