Joshs4x4toyz
Rock Crawler
If your looking for a kit then I would buy the kyosho axles and look at the traxxas or savage 2 speed trans and design a frame around it and have a one off build that is your! I have a scale 1/5 jeep with these axles and they are very well suited or custom builds of this size.
Kyosho 1 8 Nitro fo XX 4WD Monster Truck RTR 31228B Foxx | eBay
Kyosho 1 8 fo XX ve 4WD Brushless Monster Truck RTR 30887B Foxx | eBay
The kyosho is smaller with a wheel base of 14.17 inches(360mm).
Like twisted said use these axles. My large scale rigs use madforce axles and they hold up great. I use emaxx 2spd transmissions as well