Here are pictures of my deteriorated crankshaft pulley from 2000 2wd Frontier 2.4L, 153K miles, never been more north than Louisiana....
Found the problem after changing the belts and viewing the 3rd A/C ring wobble. New pulley ran me $250 after tax at a local dealer, not something the chain part stores sell.
Took me about two hours two change, no pulley puller needed, clutch held engine in place for unbolting the old one and bolting the new one to spec.
I guess I'll put the old one out of the curb for the metal scavengers...