Ok I have replaced both speedometer cables and the speedometer sticks jumps while driving, the garage says it will break the new cables if it is not fixed right. THe speedomerter was stuck on 35000 miles its a 78 so do I have to pull the dash to replace or rebuild the speedometer, could it be anything else binding wrong cables????? Help?

Does your car have cruise control? If so, it may be the transducer, mounted on the driver side fenderwell, is rusty/gummed up inside. That will cause the speed-o to jump, but not stick at a certain mph.
If the transducer is good, then the culprit will be the speed-o head itself...not an easy job to remove/replace. The dash will have to be removed to access the speedo...You can have yours repaired, or buy a new one. Either is not cheap, but you may find a used one on e-bay reasonably priced. Adams' Apple2008-02-18 22:14:22

If you do have to refurb it, try corvetteinstruments.com, very reasonable and thats all he does. he is in Florida. He has all my stuff now.

Ok will check the transducer , will it be apparent if it failed , just clean it or how do yo test it...Thanks BB78

Thanks I will keep that in mind if I pull the dash but really dont want to Hope its the transducer. will let you know Thanks for the info BB78

Mark, check out This Thread on cleaning the transducer...I think Chris has some pics posted...