I'm getting a strange noise coming from the front end when i put my 99 f250 into 4wheel drive. i have manual hubs and was wondering if maybe one of the hubs is going out. The noise is only there over 3/4 throttle or under medium stress. It kind of makes a clunck clunck sound.

 

Possible, but doubtful. Did you check for bearing or balljoint play? I would suspect the unit bearing first then possibly the hub.

 

Not yet I have been playing in the mud with it and i need to wash it tomarrow then i will check it out.

 

Check your sway bar bushings and end links, I had the same thing and that is what it was. Easy to check, get under your truck and hit the sway bar, if you hear a small clunck, that will translate to a bigger clunck by the time it hits your floorboard.

TT