I have had a faint “chirp” that I hear when the truck shifts from 3rd to 4th. No vibration or anything else unusual. Does not seem to happen in other gears and happed in just normal driving. Anything to worry about? What could it be?
Also with the 68RFE trans, chirps on 3-4 shifts (typically at heavier throttles) are pretty common on Mega Cab trucks. There is a software update for 2016s that usually corrects it. For the ones that still chirp with the new software, we've found that flushing the trans with Valvoline ATF+4 can help to reduce or eliminate the chirp.
Although the chirp is annoying, it won't damage the trans, so fixing it is not an emergency.