History:268,000 miles
Engine:V6
Drive train:4x4
Transmission:unknown

Prologue: My dad owned this truck since it was new, always had the oil changed and all the maintenance done on the truck.

Driving on the highway the explorer developed a vibration. Definitely a speed related vibration. High frequency. Not related to engine speed but definitely road speed related. Also noticed while in drive it was engine load related as in, there is a vibration when I step on the pedal, when I let up the vibration went away. Going uphill 2wd the trans just stops working. RPMs go up speed goes down. Exactly like it was in neutral. Had to pull over.

Once I pulled over I tried the switch for the drivetrain selection (2wd/4wH/4wL). Tried it in 4wH, nothing but noticed a whining sound when I put into park. Park would not work and allowed the truck to roll. Switched into 2wd and it did the same thing. I then switched it to 4wL the trans engaged and I was able to limp to a gas station. Park worked in 4wL and so did reverse.

I don't know anything about explorers so I figured I would try my truck forum. I have formulated a few questions.

1. Is the transfer case screwed up, if yes then why did 4wL work?
2. If this is a switch that has gone bad, which switch is it and can it be replaced simply?
3. The truck is sitting in a gas station about 160 miles away. So its either I tow it or I scrap it.