Had to remove the dash in the 89 GT the other day. The speedo was shaking before we removed it, now we can get it to reconnect to the guage. There isn't enough slack to connect it and stay on. Any ideas? Is there a longer cable aftermarket or extension?
You might not be getting the square center part of the cable mated up straight with the speedo, itself. When installing the speedo cable in her Capri, I had to have Frankenstang turn the other end of the cable slowly while I pushed the gauge cluster end into the back of the speedo until it finally clicked into place. (Doing this by myself while installing the speedo cable on my Notch was a major PITA.)
Likewise, when installing the VSS (Vehicle Speed Sensor) end of the cable, I've found that it's easier to remove the VSS first, plug the cable into it (allows you to rotate the gear and such to get it to mate up), and THEN plug the assembly into the tranny. Might save you a bit of a headache there, hopefully.
The VSS is at the tranny end of the speedo cable - driver's side, right next to the exhaust hangers of the tranny crossmember. It's held into the tranny with one 10mm bolt. Unscrew the bolt, and wiggle it out. Installation is reverse of removal.