[simplechamp]

Not sure on the exact purpose of the sliding blocks, or the benefits of them. If I had to guess I'd say they are to stiffen up the plastic cup, or keep the cross-shafts from digging into the plastic cup? Most 1/8 diffs don't use sliding blocks, the Savage and few other vehicles that do are actually the minority. And with an alloy cup it's one solid piece of metal, so no worry about flexing anyway.

There is a tiny bit of play between the cross-shafts and slots they go into, but there has to be a little bit to be able to slide them in and out and let them rotate. The walls of the cup and 2 larger gears are mainly what keep the 4 small gears in place. The cross-shafts are to keep them on-axis so the mesh stays right. At least that's how I see it.