Speedometer Cable Question: Aftermarket or "New Chrysler"?

A third option is a good used on from one of the a bodies being parted.
I replaced the drive cable inside my original casing once. Lasted about a year (daily driver). The thing is routed with a 90 degree bend under the drivers seat. The cable will eventually wear completely through the casing there. A good used one from a 75 model is still working today.