Jack it up on the diff and apply the brakes. Then try to turn either wheel after releasing very quickly. If it takes a while for the brakes to release then your rubber line is indeed acting like a check valve and should be replaced. Pulling on braking can also be strut rod bushings, control arm bushings, alignment either front end or 4-wheel..... In the old days some shops had equipment to grind your new shoes to match the arc of the drum. Anymore you just set them a little tight and drive it a bit with some hard stops and then check your adjustments or back it up on gravel with some hard stops and let your adjusters do their job.
