I did something similar once
http://www.rccrawler.com/forum/traxxas-crawlers/168584-long-time-coming-rock-maxx.html
Although not near as finished as yours! It was still fun, but had many limitations due to the use of uncommon, for a crawler, parts. Namely, it was heavy, had poor steering angles, was ok to crawl but with no speed, etc.
Sadly, I never had a chance to evolve it once it was stolen right off the passenger seat of my 1:1 crawler while parked on a trailer overnight.

Still, I think building axles with proven off the shelf parts like AR60 stuff that has OD/UD gears available, CroMo axles, crazy steering, etc, is the way I would go if I decided to build another set of custom axles.