The axles are solid, but they do sell optional differential gears that you can plug into them at cross-rc.com but stock they are locked solid. The axle casing they claim to be some kind of high strength polycarbonate plastic. All the inner, gears, axles etc. are all metal. It turns better then I thought it would, the wheels are very soft so they just flex around when its turning.
It seems pretty strong, I can hold my hand in front of the bumper and all 8 wheels will spin trying to move it, it has a ton of torque to it. It's very slow though I'm not sure what kind of gear ratio but its defiantly meant for off-roading.
Locking diffs would be awesome, cross-rc doesn't have any and I'm not even sure how to get a hold of them because each axle is unique for the drive shafts and steering units. You would need to find like... |- -|- -S- -S axles.
I might try to put a different transmission into it similar to the 3-speed in the Tamiya's to give it a higher top speed.
The kit also comes with pre-wired very nice lighting system with a LED driver board that has working brake lights, reverse lights, headlights toggle-able with a 3rd channel and blinkers. It connects into 3 channels on your receiver.
A few problems I've noticed though on this are the stock springs are WAY to soft, I've ordered some stronger ones they carry. The whole truck tilts a little one way. The spring design is very unique the top and bottom ends are coiled into the center and a screw is used with a washer to hold them directly to the frame and axle, there is no damper in the middle, its outside it on another mount.
Also the reverse lights are brighter then the headlights which is a little odd. I'm sure I could replace the LED's on them.
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