Jack up the axle side that's loaded when it's noisiest, and pull the wheel and brake drum. Try to wiggle the axle flange in/out, up/down, right/left, and feel for slack.

While it's still up, crawl under and turn the driveshaft and feel for ujoint slop or bind, and look for smooth movement of the spider in the bearing cups, both front and rear.

Not responsible for advice not taken...