The diferences in the Van/ Ute rear axle assemblies, & other passenger models are relatively small.
They use a larger axle bearing to help carry the load better in these commercial models.
The lower diff ratios are also intended to help the poor old A10 to handle the load.

The ute rear axle housing should bolt straight into the springs of other models & all the diferentials will interchange within all the 1000 axle housings as they are all H145's The axle shafts are the same for all 1000 models

Using a Datsun 1000 Ute [B20] rear axle assembly in a passenger model [B10] is not the same upgrade as using the 1200 ute [B120] rear axle assembly in a 1200 passenger car [B110] as the only real change is in the load carying ability [bearing size] & diff ratio [lower], however, the diff is not suitable for use behind high power engines that are driven in a high performance mode.

P.S. The Datsun 1200 passenger model diff will bolt right into the 1000 axle housing to provide a 3.9 to 1 ratio.