Old Commer

Single speed diff zed.
That is the handbrake cable at the rear, I can't see the cylinder.

Bigcam, not the diff housing, just behind the yoke, round shape sitting up about size of beer can or coke can depending on preference

Dunno Zed, but it is a single speed diff, the change motor or cable or whatever goes to one side, generally the left.

OK bigcam, I'm not too familiar with trucks, cars are fine :

The lumpy bit you can see on the diff housing is probably something to do with a plug to hold the crown wheel in mesh against the pinion. On these light pommy trucks the bearings aren't up to the job and a bronze rubber is there to keep the job aligned when the pressure is on. Usually the thrust rubber is on the side. Just guessing.