speedometer not working very hard shifting and engine rev
 

I just got my truck back from the tranny shop 3 days ago,was driving down the hiway looked down and my speedo went from 65 to 0 instantly. it was driving fine till i exited then started reving and not shifting till about 3000 rpms. So i changed the sensor on the rear end and the vss on the transfer case but no results. anything i missed or advice o wise ford fans? Please help!!!!!!!!

What year and motor?
I'm not clear about the 'revving 'part!
Do you mean just the speedo registers high rpm or the motor revs before shifting?
Are there any codes set?
Is the transmission shifter lamp flashing, near the OD button?

sorry no info
 

Its a 98 f150 5.4 with 4r100,4x4. it drives normal till about 2200 rpm then revs to 3000 and shifts and bucks like a bull. just had the tranny rebuilt, transfer case had bearings and a fork and pump hose fixed,and new carrier and axles and bearings installed in rear end. the semsor in the rear end was broken so i replaced that then the vss on the transfer case. Just got a call from the secratary at tranny shop she said the mechanic says the problem is in the transfer case come see him at 8am.i want some ammo to go in there with so he dosent gimme the buisness please. thanks for the help

no o/d light flashing either

I don't know about the speedo, but my truck would rev high before shifting and I took it to a few tranny shops to get different opinions. One guy suggested that it could be my TPS (throttle position sensor) and I thought he was nuts because it had nothing to do with the tranny. I happened to have another TPS in my garage so I replaced it and my issue was gone. He said when the TPS begins to go bad they develop dead spots and it causes a mis-read and the computer lets the truck rev higher before shifting. It's worth checking out because I was ready to drop some serious cash to have my tranny worked on.

cool thanks i just got back from the tranny shop and he told me the gear inside the trasnsfer case that runs the vss was broken because he stuck his finger in there and didnt feel it but when he spun the vss it registered on the speedo. so im going to try and replace it myself. im no super mechanic but im not paying 1000 bucks to replace a plastic gear... no way!!!!! ive r/r trans in older f250s and old mustangs so I figure gettin it out is half the battle. anybody have any advice on replacing that gear? I would like to get sum idea of what im jumping into. thanks in advance

got it fixed the keeper for the plastic gear on the main shaft on the transfer case came loose so i got a new one and reinstalled the gear. she runs like a dream now.

where did you get the new keeper???? or is that something that comes on the new sensor