you could bush any 1.6 needle bearing rocker with the right walled bushing, probably would wear better with a bronze bushing anyway instead of bare AL on a stock shaft. suppose you could go real high tech with sealed roller bearings. Thing is with needle bearings and the way they are spaced is that there is no where for a stray needle bearing to go. They are in fact sealed on both sides with either shims, spacers or rocker shaft hold down blocks. You just need the hardened shafts.
Im sure if you bust one in half, the cages may hold them, may not depending on the severity of the break.
