Does anyone have info on the different length axles used for swing axle gearboxes? A gearbox has been put in for repairs and came back with an axle replaced. Problem is now the bearing sits approx 4mm out further. Are their different spacers to correct this? Or is there a big problem here?

There are actually 3 different swingaxle lengths, but only two most common in Australia.

Either way, there is more than 4mm difference between them so you most likely have the correct one.

The axles float at the inboard end
and so long as they have not come out of the spades at that end,
it will allow the axle and bearing to slide back in and seat.

If yours had a spacer behind the bearing, it will only be about 6-8mm thick,
and all types will have a wide spacer for the seal to run on,
so hopefully that is not now behind the bearing.

As above.
Just dont let the axle come out too far and loose engagement with the fulcrum plates, or you'll be pulling the axle tubes off!

It makes sense now. At a guess I would say the a fulcrum plate has fallen out. When rotating the axle by hand there's a small clunk. Seems like the shop must have tried cutting corners and that would be why they let the spacer out. Will let you know how we go once its apart.