Glad you enjoy the setup Foxy and that is exactly the way I drive too.

If your diffs are leaking this badly I suggest you get some silicone sealant and put a thin bead around the top of the case before fitting the crown/spur gear. Diffs should not leak and if they do then what would be the point of all the alternative weight oils? Plus as grease gets hotter it to starts to liquify and then too would leak out. Now, I strongly think that either the outdrive shafts are worn down as when constructing the diffs many people overlook the need to lubricate them before you slide them into the case/crown/spur, this wears away the O-ring seal and so allows the diff to leak.

In conclusion:

1: Lubricate the outdrive shafts.

2: Lubricate the O-rings before fiting them into the diff.

3: Try the silicone sealant between case and crown/spur gears.