Call AutoInstruments, and have the speedo restored. He's a friend of mine, but I'd recommend him anyway, and here's why:
I was talking to him one day while driving my '62 Suburban, and the speedo was doing the EXACT same thing as yours was.
He told me to pull over right now, and unscrew the speedo cable, otherwise the guts inside the speedo head would explode, then they were unrepairable.
Well I thought "Yeah, right...it's not THAT big of a deal" and kept driving it.
Later that week, sure enough, it got real loud, the needle started going everywhere, and then there was one last noise, and the needle settled right on down. To zero.
So I had to find another one in the junk yard and send that to him.
The new speedo is restored, works like a champ, the number are new, the odometer is new, it's calibrated, and I'm very, very happy.
AutoInstruments: (276) 647-5550
-Brad
