Rear end noise

My 74 has a creaking noise coming from the right rear. It's only there when on the gas(any gear) and changes with speed. I had it on jack stands running but no noise? CV joints feel tight and there's no slop in the wheel bearing. Any ideas??

Does the noise change with the clutch in/out in neutral?

I found it. The axle nut was not tightened enough. The cotter pin was still there but the nut was just more than finger tight. Tightened it with my impact(probably not 250 ft.lbs but should be enough). Only sound now is the putter of the exhaust.