why not jsut buy a Kaaz or TRD lsd and put it in your banjo instead of buying a worn out 23 year old diff?? (these will cost about $700 usd - but will be the best investment you'll make for your rwd car)
AE86 diffand rear suspension is tough to find..
why not try to get rear Koni adjustable inserts (short type), aluminium lowering blocks for the leaf springs and weld on a panhard bar to eliminate side to side diff movement.. (or even a 4 link kit for an escort - ~$1200 TT before shipping from ebay.co.uk) - and either invert your leaf springs, cut and flip the mounts or remove or stack them till you get the stiffness you need.
I have also read of ppl using royal saloon front struts, spindles and brakes, and diff, spindles, srtuts etc..
i have seen allot of KE setups on Australian and NZ websites, and you have allot of options besides the AE bits.
http://www.rollaclub.com/ - check that
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