My musings on this subject:
D3 hub bush on the left, D2 on the right. For some reason the D3 centre sticks out a bit more than the D2 version, even though the geometry of the hubs and arms is identical. This means when both bushes are pressed in to the hub, the centres will touch and push the outer flange out slightly. Strangely this doesn't appear to make any difference to putting it all together.
This one is interesting - the D3 uses two different parts on the hub. The D2-style one goes on the front, and this one goes on the back. I think this is intended to provide stability under braking as it will stop the hub twisting.
I did think the D3 metal bush was intended to stop the bush squishing out of the hub like it does on the d2, but its only usually the front one which does this and the metal bush goes in the rear on the D3
This is the two of them together
Fitted to the D2 hub
D2 bush compared to the D3 one which did indeed push out slightly. This hub fits perfectly in to the lower arm though. I did wonder about putting two of the metal bushes in, but as the assembly requires the centres to move, and the metal one has to be pushed in on the actual metal washer bit (rather than the flange like the other one) it would be impossible to assemble with two of them.
B5 Lemforders fitted to the lower arm
