jus bought a quaife (complete in housing), when i spin the wheel by hand the opposite wheel spins but there isn't much resistance there. Im guessing this is normal, with them being mechanical rather than frictional.?

changed the oil too and there was a fair bit of material on the magnetic drain plug, is this normal for a new diff.? It was installed around 9mnths ago and done a couple of thousand miles in the previous motor.