Thanks 1200RC
The beauty of our beloved Datsuns is that by knowing just which selected parts from other models to use, we can build a much improved automobile without needing to do too much fabricating or butchering to achieve the desired result.

The diff ratio in the alloy diff center from the 1000 will be 4.11 to 1 if it's from a passenger model, & 4.375 to 1 if it's from a commercial model, which includes the Van / Wagon.

Now,.. which models of Datsun used a rear disc brake system that will fit inside a 13" wheel. Hmmmmm. That might be a hard one. Any of the front drive cars perhaps? Even if it is a model that was not sold in Australia. I have a 1000 model remember, so i am really restricted to the original rear axle as any replacement is likely to be too wide.

EDIT
Hang about, if i remember rightly, the original Bluebirds of the early 60's used a rear axle that is dimentionally suitable. I wonder what diff center that they used, & what brake mounting flange also. Hmmmm.

To put things in perspective, Chryslers mainstream diff was the 8" model. They were used behind even the V8 engines
The H190 is dimentionally only about 10mm smaller in the ring gear. What does that tell us.