Jeff, It might be more than you want to pay, but Arthur Jackson has a H190 rear end out of his Sunny, 4.1:1 LSD with disc brakes. He parted out the car & nobody has/had bought it when I last talked to him. He wants $2000 for it, which is what it's worth, really. You can call him during the day on 4577-2400, though he's offically retired he's working on his own stuff, namely a bike powered 3 wheeler car that'll be road registered. You could also talk to Stewart Wilkins, because that phone number is Stewart Wilkins Rallying, he might be able to help you, he only recently found the clutch fork & throw out bearing housing I needed to put a 5 speed in my Sunny Coupe. I take it Bob Moore at Budget Exhaust at Merrylands was unable to help you. You could also try Grahames Auto Wreckers at Smithfield, they seem to be wrecking the older Datsuns now, they even had some 1200 utes there recently.
You could try a H190 out of a S12 Gazelle, they need some modification to the bottom trailing arm mounting points, or have you had a look at the rear end in a Z24 powered Vanette, they're H190's with trailing arms & such, the manuals are 4.1:1 & the Autos are 4.3:1. There's your ratio's for Wakefield & Eastern Creek.