I've got the B-fast diff in and running, amazing!. I'm so used to being paranoid that the diff is going to slip that it's going to take me a while to get over but this diff is solid as and verrrrrrrrry smooth. I swear there was 8 thrust balls in the kit but the site says there's 6. Anyway I just put in whatever there was so I wasn't counting. It's a very good thing
http://www.bfastrc.com/tqracing.html