Slow build 71 Scamp 440

Ok we have noise! Not nearly as bad a 7 1/4 with the shot pinion bearing. But this sounds bad especially over 75kph. Two different noises. I’ll try to describe them the best I can. Noise one happens when I let off the gas and just before the engine starts slowing the car down. It’s like a hum/vibration. Power no noise, engine starts slowing down without gas no noise. Just that transition between power and no power. Pinion pre-load?
Next noise is at speed. Vibration hum in and out in and out. Drive shaft not balanced?

Maybe it’s the driveshaft causing all the problems. I don’t think they balanced the shaft as I supplied the shaft from a purchase made on here. Maybe it needs to be done.

Pattern on gears when done was perfect.
New and balanced tires.
New rear end 3:55 S/G
904 transmission (no change)
All rear end components new.