my 95 f150's transmission felt like it was in limp mode
so I pulled codes and found 639 - Insufficient input from the Transmission Speed Sensor.

Ok even tho it says "Transmission Speed Sensor" is it the one in the diff
or like it states the trans?

 

the one on the diff is the vehicle speed sensor(vss)

 

They've even gone so far as to call it "The differential speed senor".

On my 87' theirs a sensor that plugs in where the speedo cable goes into the tranny. But mines a mechanical speedo. No Haynes manual?

 

As far as I know the differential one is the only one. I don't think the E4OD has one inside, and it certainly doesn't have the mechanically driven one on the outside.

 

if it does, its in the solenoid pack, i've swapped E4OD's and theres only a harness to the solenoid pack, and the MLPS

 

Crap sorry was tired when I posted that.

The Trans is a 4R70W (AOD-EW) I do have a VSS and TSS.

 

I was told that transmission didn't come in our trucks and that it's most likely the E4OD.

 

Odd my 95 has always had the 4R70W and when I bought the new 4R it looked like the old one casting number and all.