Check to see that the wheels are locked don't bother to see if the wheels are locked your truck does not have manual locking hubs. it is an automatic system which uses a vaccuum to engage the front axle. if you look at the back side of the axle you will see a few wires going to the right side. if this system is not engaging the front axle then you will not have four wheel drive as long as you have an open differential in the front. if you have a locker or a limited slip in the front then you should still have 3 wheel drive with the drivers side front being the only one turning. if this isn't the case then your transfer case is probably the culprit. http://dodgeram.org/tech/repair/4X4/cad_mechanism.jpg
I would start by checking vacuum lines
probably a vacuum system leak. Older dodge trucks had the front transaxle engage by a vacuum line. Make sure your pump is working, and that there are no leaks. Then it should engage
If it has 4-wheel drive you would see controls on the dash to engage 2-wheel high, 4-wheel high or 4-wheel low.
on almost any automatic 4 wheel drive the gears that engage the hub could be stripped out or stuck cause if you know what the gears that engage the wheel than you would know that they are fradgile lookin but that is what im thinkin it is cause that's what happened to my truck so you probally need some manual hubs to make sure they always work or the problem might be that your transmissoin to the front wheels might be jacked up I don't know Fords that well, but many 4 wheel drive use a small motor basically to engage the 4 wheel drive. These can go bad or become stuck. If you engage the 4 wheel drive with a switch, it is this type. Could be the motor, the switch, fuse.
No! a 1987 cutlass is rear wheel drive, the van is front wheel drive....wrong offset.
The CV joint would have to be broke in 1/2 to cause the 4-wheel dr. not to work. 4-wheel drive would work BUT the front wheels would not pull.
Four wheel drive tends to be lighter, and less complex.. with a six wheel drive (such as in the M35, M39, M913, etc. series military trucks), you usually have to have an interaxle differential lock. In normal operations, tandem axle trucks, such as dump trucks, tractor trailers, etc. only have one axle which drives them forward. When they need to, the driver can engage the differential lock to engage the second drive axle. On a 6x6 truck, such as the type described above, the transfer case would be used to engage the front axle.
V8 auto would be a 46rh
LOL, the old rims had a hub lock on them, you need rims with hub locks for a 4 wheel drive truck somtimes.
If you have push button 4-Wheel Drive, it is recommended that you use it every once in a while, in order to keep gunk, rust, and corrosion to build up on moving parts. The mostly likeley (though not definite) reason would be that you let the 4-wheel drive unused for so long that corrosion has built up on the parts and the actuator that engages the 4-Wheel Drive doesn't have the power to engage it past the corrosion. You'll most likely need to take it in to be cleaned, or to have parts replaced. In the future, every month or so, engage 4-Wheel Drive and drive around in some mud, grass, sand, or any other loose ground for a bit, just to keep the parts moving and clean.
check the power steering rack or the steering pump
could be the 4 wheel drive module located behind the glove compartment. If you don"t hear a click when you press the button to engage the module isn't working.