Had the same problem on my Cat. Turns out, as usual, the left side drive bearing was totally shot, and it snapped the speedo cable link. Common issue. Remove your driveshaft and replace the bearing, you should be all set.
Raise the rear of the sled, loosen the rear adjuster bolts for the track, put a bunch of slack in the track... Reach up from underneath on the left side, grab the drive shaft and try to make it move off the center of the turning axis. If there's any play in there, you have a cooked bearing and it needs to be replaced.
Unscrew the speedo cable from the end of the shaft (you'll have to remove the belt and the secondary to get to it). Clamp the end in a cordless drill chuck, put the drill in reverse, and pull the trigger (gently at first). If that cable doesn't spin freely, you need a new cable.
If the cable spins freely and your speedo STILL doesn't work, you need to pull the cable from the speedo and check functionality up there.
Incidentally.. Pulling the secondary and removing the cable are steps toward replacing the bearing.