plastic gear in tranny to hook up speedo.?

[BUXMAN66]

thanks guys,i noticed that when i first got the truck the speedo was working, jumping, but barely working.since i disconnected both ends and pulled the cable completely out of the cable line housing,cleaned it, inspected it,and sprayed it w/a industrial type graphite spray,and reinstalled it,now nothing happens.before it would at least jump at 'round 35-40mph.thats what led me to believe that a plastic or a wear-prone- intended part had failed.i'm goin' to take it to a local tranny shop and let him check it out. at least now i have somethin' i can point him toward to look at.thanks again!