I changed my speedometer cable & housing 2 weeks ago (68 gtx/727) since the housing had a hole burnt thru by the header. I noted that the replacement assembly was considerably longer than the old one (80") but verything worked fine. I also changed to the correct pinion gear, ensuring that the cover was indexed correctly. Now the speeometer needle stops on 20 mph rather than "0". Any suggestions? I was told that possibly the grease I coated the cable with may have gotten on the delicate springs in the speedometer itself. Appreciate any ideas you may offer.

I just went through this same thing. The connector on the end of the cable has to go straight into the back of the speedo. If it's cocked to one side even a trifle amount, the speedo will not completely drop back. I've seen them go up to 60 and stay there until I wiggled the connector a bit. Pull the cable out of the speedo and re-install it as straight as you can, and make sure it fully seats. Has worked for me a few times.

Also, the 80" cable is too long (should be around 68") but will work, however, make sure if you loop it, to loop it outside of the firewall, not in near the speedo. Hope this helps!

polkat, Thanks for the info. I can't get to the car for a couple more days. But when I do I'll try your suggestions & give you some feedback. Seems all the speedo cables are the same now. Checked a few places and all were the 80" ones.

NAPA has the 68" cable. The part number is BK6151659. It's roughly $19. This one was listed specifically for early 70's A bodies, but fits a lot of others that have the snap-on plastic speedo connector.