What is actually the very best (for racing/hi-perf) is to use 3/4 grooved bearings... the top should be fully grooved; the bottom should be grooved at the outer edges ~25% per side so to allow the bottom to be solid. That design is proven to provide the bottom thrust face being solid to absorb the greatest amount of force. I think Federal-Mogul (via their "Speed Pro" line) sells 3/4 grooved bearings. ("Fully-grooved" is yester-year's technology.) You can call the Federal-Mogul Tech-Line and discuss this with them.

Mopar Mitch "Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers! Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!