I have a 2014 Dodge Ram 2500 standard cab long box. It makes a gear howling noise in 2wd only. In 4wd the noise goes away. Dealer already changed the transfer case and it made no difference. Now the dealer is stumped. Anyone else having this problem?
Wild shot in the dark, but could it be the front differential? Once you engage 4x4 it puts it under a load and changes the pitch? Check the lube, see if it has a lot of iron filings. If lube is clean, perhaps add a bottle of Mopar friction modifier?