HELP! No speedometer, shifts hard, od light blinks

[harv543]

just randomly the other night my speedo jumped high, pinned to zero and truck started to hit excessive high rpms with hard shifts and od light started to blink, the speedo used to wiggle a lil and was off by a couple mph but never bothered me. I've replaced the vss in the diff and now the speedometer wiggles a lil bit but not past 15mph! What tests and tinkering could I do too quickly pin point the issue and not have to mess with the differential?

 

[miesk5]

yo HARV

I replied to your other similar Q yesterday at http://broncozone.com/topic/18552-harsh-shifting-while-driving/

See my last two replies.

GL!