if you can identify the wheel that the noise is coming from that would be the place to start. if you are willing and able to get under the MH there are two rubber plug on each wheel backing plate, they are about 1 inch long and 3/8 in. wide take them out with a small screw driver and with a flashlight you can see the side of the brake shoes, a new shoe is close to 3/4 in. thick, there should be a line around the side of the shoe at the 1/4 in. thickness, that is how DOT checks them on trucks. anything less than 1/4 in the rivets that hold the lining to the shoe will be wearing into the drum and the bakes and drum are not safe to operate. with a lot of mountain driving also it is possible that the shoes are cracked sometimes that is visible through the inspection holes. if the shoes are good and no cracks it could be a accumulation of brake dust in the drum causing the noise. a high percentage of over the road trucks have the rear axle brake covers removed to prevent dust accumulation
