I've got a 01 supercrew 5.4. Anyhow, I was at a friends house the other day and we had some heavy rain. Needless to say his driveway got pretty sloppy and I started to spin.
I turned the **** to 4 lo and I heard the transfer case lock in and the truck did a little jerk. However, the front tires are not pulling at all....help!

 

You engaged 4 low for a sloppy driveway? That must have been one nasty driveway.

Okay, 4-hi is capable of shifting on the fly, but 4-low requires that you are in neutral with your foot on the brake to engage. If you tried to go straight into 4-low while moving it would likely not lock in the front axle. Engage 4-hi and see if the axle is locking in, and if so, switch it to 4-low just to double check. It sounds like it may have just been a user error (I am assuming, but I have been wrong many times before ).

If the above is performed and still no front end lockage, you may have an issue with the hubs locking in (not sure how they works on the 97-2003's).

 

The front hubs are not engaging. It useds a vacumm from the passenger side / rear of the the engine comparetment. A real easy fix. Sorry, I'm at work right now and can't get into it more. Do a search, you'll find everything you need to know to check which part is bad. Brian.....