I own a 84 chevy. When driving down the road in 2the wheel drive a rapid clicking sound begins to come from the front axle. It sounds like a baseball card in a bike tire. If I slow down the truck "jumps or "jults" the clicking will stop and I can continue driving. It never happens if I leave the truck in 4 wheel drive. I almost think my automatic hubs are trying to engage in 2 wheel drive. Anyone thoughts??