Thanks for the reply.

I got the front shafts changed when I got the CV's done (boot ripped and cheaper as you know to replace all of it, rather than the CV's themselves). They were fine up until the transfer actuator went, but knowing my luck, they could have developed a problem at the same time

The front bearings were done at the same time as the actuator, so it is possible that they weren't done right.

I must admit, sometimes the "moan" sounds like it might come from the rear but more so the front, but as mentioned, you can feel the slight vibration in the floor, gearstick and steering wheel.

Rob