guessing that you have one fo the central axle disconnect systems. the transfer case vacuum switch, and the vacuum actuator on the axle are both prone to failures, but easilly replaced. there are numerous aftermarket kits to convert to a manual, cable operated system, adn remove the vacuum components entirely.
Access in rear door panel, allows you to lock/inlock rear door.
No. The axles & suspension are completely different.
axles ue 75w90 t-case uses ATF
I believe it to be the transfer cases.
Probley have a bad 4x4 Actuator in the front left side of the differential HOUSING. It is towards the center of the housing on the left when standing in the front of the truck.
Dana 44 front and rear
usually somewhere between one and three. Do you have power windows?
Locking axles was not a factory option. Limited slip rear axle was an option. many aftermarket options are available.
The most common cause is a vacuum leak in one of the hoses that lock the hubs, if that checks out OK then the solenoid may be bad. Good luck.
On the axles, just before the hub and brakes.
The front and rear axles are differentials.
Dana 35 and Dana 44