If it is the rebuildable type then pop down to your local bearing shop and order the size you need. You will need to extract the bearings though and measure up first.
if you can knock a bearing off the axle then its game on if not its not last time i checked the gigapipe is not ment to be rebuild-able you can get the skf isis bb for cheap if you shop around and it'll last years and miles longer than the truvativ ones