My 69 912 Targa:
Miy speedometer did not work at all when I bought the car.
I had to replace the speedometer drive off the tranny, was worn thru the diecast body. Then I had a jumpy speedometer at the low speeds, changed the speedometer cable and all is well.
The PO gave me a new cable and I discovered after I removed the entire old one that it was 11" longer but I tried it anyway and it seems to work OK. Measure your old one before you buy the new one. You can buy the core alone from Stoddard so you don't have to go through replacing the cable jacket.
Don't forget to add a speedometer cable rubber boot at the transmission connection is you don't have one.
Good luck
Ron D
