First snow, first time plowing snow and in 4WD since last winter. There is a ticking sound coming from the front when 4WD is engaged. Ticking is faster with speed - like 4 ticks / second at around 10 mph. I'm thinking u-joints on the front drive shaft but haven't wanted to lie down in wet to frozen slush to check it out yet. The u-joints on the front are original from 2001. It doesn't sound like bad half shafts. Do you think that's it?