speedometer sensor???

I have been having a weird problem with the speedometer sensor on the back of the transfer case. Every once in a while, (5-6 months or so) my jeep starts driving funny, the speedometer is way off, Like say Im doing about 45 mph the gauge reads 90-95mph. It starts to shift funny and sputter and cut out. it is practically undriveable. So in the past, I have just went to the junkyard, and got a new one, bolt it up and its fine for another few months. Well, its really starting to piss me off so I want to fix it once and for all.

So, anyone have any ideas? The first time it happened probly 2 years ago, the plast gear inside was all shredded up, but the other times the tooth has been fine, and is probly just the sensor itself. I have already tried electrical grease on all connections and that helped for maybe a half mile of driving, and it went right back to the way it was. Its really starting to piss me off. any help is appreciated.

Get a New one and make sure you get a new plastic tooth gear and make sure its the right teeth for your tires and gears. also make sure its aligned to the proper mark on the sensor and t-case tab. other than that... there shouldn't be any more issues...

bad cable maybe?

well, got a new one yesterday, completely fixed the problem, got it all set up right, so well see.

- NEW PROBLEM -

but now I've got a new problem, and figured I wouldn't waste the time setting up a new thread, so hear it goes. Ive got a real bad vibration all of a sudden, it seems like its coming from the front. the u joints in the driveshaft seem fine, and the pinion angle is good, but it seems loose where the yoke goes into the pinion. I just had my gears set up less than a year ago, and I do regular diff fluid changes. also a brand new pinion seal. But I don't know what could be wrong. Any ideas?