Yup, that's what it would sound like
Block front tires
Put trans in neutral
Jack up rear wheel(s) and spin
If you hear the noise remove tire and then brake drum(use jack stands at this point), brake drum might need a few "taps" with rubber mallet, or block of wood and hammer to break it free of the axle, they often get a little rust near the lug studs that needs some persuasion.
Look at the brake shoes and replace if they are worn down near the rivets.
Rear brakes on pickups often last 3 to 4 times as long as front disc pads.
You could just have a broken spring and one of the shoes is rubbing the drum, or it is simply time to change the brakes.
Rear brakes on a pickup are not used as much as the front brakes, which is why they still use drum brakes on light trucks, they are lighter and have less drag than disc brakes, so are simply better to use on front heavy vehicles.