1991 Toyota Pickup METER CABLE AND METER GEAR

If this is a mechanical type speedo drive there will be a cable attached to the rear of the gear box, look here first.

But the speedometer would be the speed sensor on the tranny (I think)

I stand corrected, this is an electronic speed sensor type, it is located on the L/H side of the transmission at the rear.

There is a cable that comes from behind the dash and goes through the floorboard of the cab and I traced it all the way and plugs into the back end if the transmission. So do you suggest I replace that whole cable or wire and plug?

Normally it is just the speed sensor in the transmission that is faulty.

Yeah I unplugged the wire plugged into the passenger side about half way down on the transmission I put a volt meter on the wire I unplugged and the light turned on so I'm hot all the way up to the plug at the transmission. Then I unscrewed the cable that is at the very back of the transmission and pulled it apart and that was the Tachometer and that works so what should be my next step ? Should I pull the whole dash apart?

Ok I took the dash all apart and pulled the MPH gauge and I got to looking at it really close and it looks like a small fuse on the back of the speedo itself when I disconnected the cable that goes from the back of the speedo to the back of the transmition it stopped the Tach from working I thought that was wierd. The fuse that looks blown is located directly on the back of the speedo but it is a permanent fuse it is sodered in. Does anybody know if I can buy just the fuse or am I gonna have to buy the whole speedo gauge? I ran a jumper wire acrossed the fuse but did not work what do u think.

I doubt that it will be a fuse if it is soldered in, this is a job for an instrument fitter, if you're not careful playing with the dash circuit board, you may damage it.