jack up the truck as high as you can on the drivers side to minimize the fluid loss & pull the adapter/speedo gear for a look see for any damage & first note the clocking on the adapter to see if it matches the teeth count on the speedo gear when you pull it. holler back. EDIT even further before this, you might put a piece of the speedo inner cable in the adapter & start it & see if the cable turns smoothly without jerking (grab it with a glove to put some pressure on it) and you might stick the cable in the speedo housing if the other one still has the needle intact & spin it with your drill & see what happens. MORE EDIT & iirc you spin the drill CCW