low speed downshift moan

[boatpuller]

my 05 silverado z71 moans and groans when cruising at parking lot speeds on the last downshift,louder when good and warmed up,service manager drove it,they checked the computer,called about tsb's.they could hear it but couldn't indentify any problem.should i get another opinon.it's almost embarrising to have a new truck sound like a 1664 international transfer case downshifting.