Speedometer crazy

Ok guys, as I work through the issues on this bronco of mine. My next project is the speedometer, is bounces - usually 3-5 mph and at most speeds above 30 mph...at 55 it bounces from 50-60 and sometimes settles out around 55.... Is this more than likely the VSS....rear somewhere else that the parts stores list it as the rear abs sensor

yo KY,

Could be VSS;

PSOM Pointer Waiver TSB 96-21-11 for 92-96; "..The speedometer needle may waver and or a light surge may occur on some vehicles...This may be due to slight dents/chips in either the exciter ring or the Vehicle Speed Sensor (VSS) and air gaps between the VSS and the exciter ring. Any slight dents, chips, etc., in either the exciter ring or VSS will create needle waver. Measure air gap between the VSS and exciter ring. It should be 0.38-0.51mm (0.015-0.020"). Check exciter ring runout per the same ring gear backface runout procedure of the appropriate model 1996 Powertrain/Drivetrain Service Manual, Section 05-00. Make sure the exciter ring is mounted correctly to the ring gear. If runout is more than 0.1mm (0.004"), perform the differential runout check per the procedure in the appropriate model Powertrain/Drivetrain Service Manual, Section 05-02A or 05-02D, to find cause and repair as needed. If all items listed above check good, replace the Instrument Cluster Assembly.

G7 CHECK SPEEDOMETER CONNECTOR

•Verify ground on Pins C1-03 and C2-01 with key in RUN.

•Inspect instrument cluster connectors and ensure proper fit. Inspect for loose or corroded terminals. Verify locking tabs are in place.

Is resistance less than 1 ohm?

YES REPLACE the instrument cluster

NO SERVICE wiring harness and fuses as required. VERIFY proper operation

Wiring Diagrams @

http://www.diesel-dave.com/vehic/manual/stj/stjd1014.htm

and http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=4921

Hey guys, I just replaced the sensor in the rear differential, the old one has some pretty significant scarring on the bottom side....what may have caused this and is my new sensor going to have the same outcome??

You may have a broken tooth in there with metal flying around. The only way I know is to open the differential and check for metal and broken tooth/teeth.

>-

I may open it up this week, I need to check to see if I have a ltd slip and need friction modifier stuff

Ok, just looked have a axle code of H9 on the door sticker. Appears to be 3.55:1 limited slip....so my next question, what do you guys recommend as far as gear oil weight, type, and how much friction modifier

90W gear oil is normal.