I'm assuming you mean the 'big' bw 78 diff out of skylines and bigger holdens/fords etc?? If so I might know of someone with the gears, but would have to check. I've definitely got lsd carriers (the whole centre section) which would likely require new lsd cones (can be had for around $120-150 brand new from some diff places in melbourne). if you can find another source. The lsd carriers I have are for 2.77 gears. That means where the crownwheel attaches is shifted sideways by about 5mm to help it clear the larger (with more teeth) pinion. You can run these with non 2.77 gears, but you'd need to make a spacer plate/ring up to reposition the crownwheel closer like the non 2.77 carriers do. There's some speculation that the 2.77 carriers won't fit in a housing not originally made for them - all I can tell you is that that is categorically not the case in chrysler housings, and can provide pictorial evidence of such (*if I can find the pic, or else I'll take new ones)

I'm in melbourne, so not sure whether it'd be worth freighting it up or not. Let me know if it's any good to you, and I'll enquire about the 4.1 gears and go from there.