I've got an '82 K25. While pulling a trailer with an 8000 lb skid loader on it out of a field last night I started to hear a grinding noise coming from the driver's side of my front axle(10 bolt 8 lug). The noise only comes when I've got it locked into 4low or high and get on the gas. It's fine if I use a light throttle, then when I get on the gas, it grinds. I jacked the driver's side up and checked things out. I locked both hubs and moved the wheel back and forth. I don't see any play in the u-joint as this was my first guess. The wheel bearings seem fine as well with no play. Does any body have any guesses as to what is wrong or what I should look for as I tear into it??