In searching down a "ticking" noise that I have been hearing lately at low speeds with windows down, I have been led to the transfer case. When I turn a rear wheel by hand, a periodic ticking seems to come from my NP208 (when I am laying underneath the truck). It is not very loud. I can only assume that having some torque through it makes it louder. I am also confused by Nuetral on the T-case. My front and rear driveshafts turn together in all settings except 2H. Is this normal and the Nuetral only disengages the T-case input? Is the ticking due to a worn chain? It ticks about twice for every driveshaft revolution. The U-joints and rearend seem the same as always.