The fork replacement could depend on which manual transmission is in the truck. The top has to be removed from the transmission. If the floor center can be removed with enough room to get the top off then it can be done. With carpet and seat removal it is often easier to remove the transmission.
You need to replace the speed sensor on the rear of the transmission.
All of the shift linkage should be internal. You will have to remove transmission, split the transmission in two to access the linkage.
On a 1996 4runner the transmission shift solenoid is under the pan in the valve body. There are two shift solenoids on the 4runner.
The transmission must be removed. Not a DIY job unless you are skilled.
The Neutral safety switch is located on the back of the automatic transmission. it is quite simple to replace. It is probably easier to replace from under the vehicle, but it is accessable from the top if your vehicle is not equipped with ABS.
It is inside the transmission
just so you know everything has to be taken off the front end of a 96' DeVille to remove the transmission, includind the fenders.
It's on the drivers side of the transmission.
It is bolted into the transmission valve body. You will have to remove the transmission pan to get to them.
Check transmission fluid level Change transmission fluid and filter
The cable between the shift lever and the transmission may be bad.
may just be a transmission sensor - $20 part - start there...