what could the noise be

[mattsrallye]

Just the drivers side one as that was the one causing problems, we do have a passenger side one floating about, would it be worth changing that one to

I asked because when the intermediate bearing on my drivers side driveshaft failed it started making a strange noise depending on load, so it would be noisy accelerating, then quiet when cruising, but if you've already replaced that then you can rule that out.

ETA if the noise varies with revs rather than road speed then it shouldn't be a driveshaft issue, could be input shaft in the gearbox, clutch, something like that as they change rpm with the engine.