I've only broke one on my Rusty, and that was from a silly-hard crash. The inside joint just popped apart. I figured it was probably weakened, so I stole one off of the nitro rusty I got from you. I noticed the shafts on the nitro were a little bit thicker. The pins on the metal part of the joint are actually a little longer, but the ball is the same size. I had to put the outdrive part of the joint from the vxl shafts(part that goes on the tranny) on the nitro shafts, and they fit perfect, with a little bit of the pins sticking through the ears on the shaft. Which should be stouter than the way it comes from the factory. It looks like the shaft would actually have to break to come apart at the joint. The stub shafts are the same length and diameter, but again, the plastic part of it looks thicker. I've read that the 4x4 Slash/Pede axles are an upgrade for the 4x2's as well.