Its pretty good.
You ahve a few options for making it a nice tight fit.
Option one is to spend some cash and buy receiver tubing, whic his seamless and fits pretty snug. But I believe its pretty pricey, I've seen people pay $25+ a foot for that..
In my case, this is standard square tubing. If the fit is too sloppy, then what you can do is weld some additional material to the inner shaft and then grind down to make it snug.
Most people do this by welding a fat bead down each corner thne grinding to be more square. I've also seen people weld thin (24 gauge) sheet metal to the flats then grind it as well.
I didn't do much with mine, and will see how it works and adjust if necessary. Only had it up to about 20mph in 4WD so far. Once we get some heavy snow, I'll try it at higher speeds.