Chevrolet Repair: 1990 GMC 4x4 5.7 l V8, gmc 4x4, tractors

Question
My spedometer stop working, but at times it jumps up and down.  What part do you think has gone bad.  I work on cars, trucks and fram tractors.  I'm just looking for a directions to start at on this problem.    Thanks.

Answer
Hi Ryland, The first place is at the transmission. Follow the cable to the rear of the trans. Now remove the cable from the trans, next remove the part that the cable was screwed onto. Now take a look at the plastic gear that goes inside. Should have wear on the middle right, replace that gear and you should be all set. I think a dealer is the only place that carries these but I'm not a 100% sure.

      Let me know how you make out       Mark