Thanks for the continued replies. I have considered belt alignment, but it is a distinct electrical whine. Not coming from a pulley or the belt. Swathdiver, I believe you're talking about the variable rate charging system. I've disconnected the sensor and there is no difference. Swapped back to stock tune, no difference. I'm just going to try my best to ignore it since I'm planning to trade in the truck soon. Then it will be the dealer's problem... it doesn't affect how it runs, just annoying as hell. I've put about 25k miles on it with the whine, still runs great, just drives me insane. But any other ideas are still appreciated.