ok so i went to the mud bog yesterday and went ahead and ran it even tho i had the noise that was questioning... I have plenty of axle fluid... but anytime i just go to lock in my hubs i hear a banging noise but i can also feel it like its beating my cab where my brake pedal is. drive shaft has bairly any slop in it when i move it up and down.. like 3/8 of a inch both ways. would it be drive shaft, spiders, or u-joints?

 

Drive shaft should not have 3/8' slop.....suspect u joints or worn slip joint

 

OUCH! Seriously 3/8" of slop... you are lucky the front DS is still in the truck.