Beginning on the upper axle gearing, here's a shot of the gears before and after installation.

Here's a close-up shot of the gears installed.

And with the gear covers installed.

On to assembling the differentials. I found these steps to be particularly interesting so I took lots of pics. Here are the parts that make up a diff. There's also a spacer that goes between each large bevel gear and its respective half of the diff case, but I forgot to show them. Note the tab on the end of the one half axle that fits into the end of the other half axle. This allows the axles to spin against each other while maintaining a ridge assembly.

Here's the axles together along with the large bevel gears and two of the three small bevel gears.

And here's a test fit of the entire assembly less one half of the diff case.

And a close up. I left it like this for quite some time just playing with it. There's something endlessly fascinating about watching gears interact with each other.

Now I took it all apart again to pack the diff with grease. I used CRC Sta-Lube Muti-Purpose Marine Grease which is a thick grease that is described as a "distinctive tacky grease".

This step was a little tricky. I wanted to pack in as much grease as possible, but I didn't want the grease to ooze out on the diff case screw holes because the screws and screw holes need to be coated with thread lock (I think I'm rightly assuming that grease and thread lock don't get along). What I did was lightly pack the diff case and fill in the areas to be occupied by the axles. In this way I was able to assemble the diff case without ooze. But then the grease was put under pressure when I shoved in the axles. Edit: I would eventually clean out the grease and fill the diffs with JB Weld. I further explain this in TXT-1 Mods: Part 1.

This pic shows everything back together and resting in the lower axle housing.

And the final assemblies including the upper axle housings that I assembled above.