I have a '99 LT 4 door 4x4 and I always use the parking brake when I park on a hill, it's a habit I picked up from my Dodge (parking brake almost worthless too) but anyway, this is very strange. Not too long ago I put the brake on with it in neutral and it started to roll back with no resistance, but when it stopped I put it in drive and it lurched against the brake. Gave it some gas and it wouldn't move at all. It seems it will not grab if the truck tries to roll backwards (which is anywhere I would use it) but you could park on a 45 degree slope pointing downhill without movement (which I did). It could use brake pads but could that do this? thanks for your input, I think this is very strange.

 

Nobody? I made a video, be forewarned it's not very good quality, but it does provide some proof that I'm not completely insane

Since I have no idea how to embed the video, here's the link for anyone that might be able to help:
http://www.youtube.com/watch?v=yyrAQqqiFq4

It's on the crest of a steep driveway pointing downhill first then I move it so it's pointing up hill in the same spot.

Any help is appreciated because I can't afford a mechanic to look at it

I guess it embedded automatically....

 

Mis-adjusted parking brake bands? They work better in forward than they do in reverse. It could also be a problem with the drum portion of the rear rotor. Rust buildup, etc.