3650 Tranny Problem

My car (2008 Bullitt) is making a metallic tapping sound at 1500-2300 rpm after it warms up. Sounds like an old & worn lifter used to sound. It is consistent with rpm whether I'm driving or its in neutral. The motor is 100% ruled out by the dealer tech. Outside tech from Ford confirmed its not the motor after dealer had it two to three times and could find nothing.

The outside tech decided that the noise is the reverse idler gear in the tranny. Keep in mind, this occurs whether its in reverse, forward gears or neutral. Could this be BS?

Anyone else see this problem before? Know of a fix??

The tech wants to see the car from time to time and make a final decision before warranty is out as to whether he replaces the tranny. He said he's seen this before but I have the impression they don't have a clear fix. I may be wrong.