Here is simple live axle for your RC MOCs. 

Features custom 2L drive ring acting like the locking element. Works OK, but not 

The print file has to be separated into objects in case you would like to modify the data or print only some parts.
You will need some L3GO or compatible bricks parts to assemble it. 
It fits all modern differentials.

The axle adapters are 3L and 5L wide, making the assemblied axle approx. 21-23 studs wide.

I suggest you to print the ball joint connectors if you would like to use the axle with the planetary wheel HUBs.
[https://makerworld.com/en/models/413715#profileId-315719](https://makerworld.com/en/models/413715#profileId-315719)

Live axle adaptors of different lengths and angles:
[https://makerworld.com/en/models/515959#profileId-432228](https://makerworld.com/en/models/515959#profileId-432228)
more to come

EDIT - added version with more details on the diff cover
Added new version of the 2L drivering and deleted the outdated version.

Added Dual output version option:
[https://makerworld.com/en/models/1914313-dual-output-diff-lock-axle-housing-for-brick-mocs#profileId-2053228](https://makerworld.com/en/models/1914313-dual-output-diff-lock-axle-housing-for-brick-mocs#profileId-2053228)