Speedometer jumping around help

dan0340 said
Do you have a link of where I could get a new one?

New Old Stock Mopar.
Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists

Imported replacements will be available for much less through your parts house of choice.
Pioneer CA3002 at O'Reilly's, AutoZone, Summit, Rock Auto...

NAPA and Advance look like they may have something that'll work, but other choices look better.

Layson's has an American made reproduction. Part number IS-663. You'll have to get through their website on your own.

OER reproduction. Probably an import. I have no idea if it's any good.
1973 PLYMOUTH DUSTER OER 3592360 OER Speedometer Cables | Summit Racing