I saw these on my buddy's truck. HPI Savage hexes.
They fit perfectly.
No more slop!!!!
I suggest you also pick up 2x 3982, Traxxas teflon washers.
I noticed the axel can slide a bit if you don't use the washers, probably not a big deal but I wanted it perfect.
I used 5 washers per wheel.
(except for the washers of course)
This holds the wheel tight, I have 0 slop in the wheels now.