Correct me if I am wrong, but I am pretty sure his 95 year 4runner has an electronic
Speedometer. There is no cable, just a speed sensor on the right
side of the transfer case near the output shaft.

This has a 4 wire connector, 2 go to the computer, 2 to the speedo.

I have had good luck removing the sensor and gear unit, cleaning the sensor portion
With electrical cleaner and replacing all the o-rings on the unit and cleaning
The contacts on the plug.

The sensor itself rarley will fail as it has no moving parts (sensor itself)
Normally they fail if the rubber membrane that seals it leaks trans fluid inside.

Often when u remove it you will find that the o-rings have been leaking and "can" cause
issues with the magnetic hall sensor accurately sensing the revolutions and can result in issues.

Other issues could be:
-the gear is damaged, causing jumping  as teeth could be missng.
-Loose wire connection between speedo and sensor
-The stepping motor in the speedometer has issues or is sticking