so my speedometer isnt working so i checked the cable and cluster and no problems . next i went under the truck and pulled out the plastic gear from the trans and it looks like its in pretty good shape .

next i realized the metal drive gear on the output shaft spins freely and i can move it back and forth ... im guessing this is the problem ? can post pics but i think i explained it pretty well

what do i need to do to replace or fix this ?
the truck is a 91 pickup 2wd 22re