Right. That was in the past that they used universals over CVD's. There's a reason they are included in the kit when ae made their own universals. The new RTR, FT, and Team built trucks are all 3/16's. The old tub sport kits, and first run of RTR's had the 1/4" axle. They have done away with that size, because it was more wheels the shops had to stock. You can tell a 1/4" axle because it tapers where the pin is to a bigger shaft to go through the bushings, and the wheels also have that 45 degree taper to them.
If you run CVD's, best thing you can do is pick up some CVD boots or put a piece of shrink tubing over the ball on the bone so the pin can't come out. It will chew the arm real nice if it does.