Here are the stock JRX2 axles on top of the XXT "conversion" axles for the GTX/NXT (and LXT).

Here is the stock Losi axles next to an AE alloy axle:

Here are AE axles installed, then the GT wide AE axles installed:


I personally use the stock Losi front axles, with a spacer from the rear end inside to use B4 wheels. I did the same on my TCP (it uses Losi axles up front too).