There is a cable for the front differential. One end goes to the front differential, one end goes to a vacuum actuator under the battery. That is what most commonly is wrong with those vehicles.
85W90 gear oil.
I believe it's called a trans-axle output shaft seal. Could also be the front differential pinion seal.
if its rear wheel drive then check differential and if it is a front wheel drive car or diferential is fine then a gear in the trannsmission is sheered
If that is the vent hose for your front differential it does not connect to anything One end connects to the differential and the other end goes up high enough so water doesn't get in ( as far as i know )
There is no vacuum switch. There is an electric actuator on the front left of the front end assembly right in front of where the cv shaft goes into the differential case and an electric actuator on the rear right of the transfer case.
When a front differential goes bad, you may notice symptoms such as loud noises coming from the front end, difficulty steering, vibrations, or the vehicle may feel like it's slipping or shuddering during turns. It is important to address these issues promptly to avoid further damage to the drivetrain.
As far as I know that is a vent hose and it just goes in an upward direction somewhere where it won't get damaged
Differential oil will work fine dude or even gear box oil.dude
The driveshaft.
No, you can also pull out the whole engine. Yes, it is a bad design. http://www.ncttora.com/fsm/1990-1995_4Rnr/Toyota.4Runner.1990.1995/FSM/95toypdf/95rmsour/1995/954runne/eg2/lubricat/oilpump.pdf Step 2: 2. 4WD: REMOVE FRONT DIFFERENTIAL (See SA section) http://www.ncttora.com/fsm/1990-1995_4Rnr/Toyota.4Runner.1990.1995/FSM/95toypdf/95rmsour/1995/954runne/sa/frontdif/assembly.pdf Some people have had sucess with unbolting the engine mounts and raising the engine slightly. To get out the pan, however, requires disconnecting steering linkages. Make sure you mark them well so it goes back in straight.
Power goes from the engine through the transmission to the differential to the front or rear axles. If it is all wheel drive it has a transfer case or center diff. between the transmission and the differentials.