Speedometer not working.

[tattooboy37]

I cant seem to figure out my problem be reading thru these threads. I assume that both the speedometer and odometer both work off the same cable. I have a 63 c20 w/ a 3 speed manual (column shift). When I drive it the odometer turns at a normal looking rate, I haven't gps'd it, but I seems pretty normal. I get nothing on the speedometer needle. When I pulled the cable from the tranny and spun it by hand the speedometer needle worked fine. I plugged it back in to the transmission and still no speedometer but the odometer still works.
? How can the cable be spinning to work the odometer - seems the connection in the tranny is good , right? but not work the speedometer? Plus I can spin cable by hand below and it works the speedometer needle, so that connection seems good, but why not while driving even though the odometer is working. doesn't make sense to me