I've got an RMO 13-145A tranny. Lately when deccelerating and in 7th position direct drive, sometimes in 7th overdrive position too, I get a harmonic hum with a buzzing sound. All else works normal. Only happens when coasting/ deccelerating between 35-45mph. Anyone had this experience? Im thinking a worn output shaft bearing, but wanted to get some input from the experienced folks in this forum. All help will be greatly appreciated.