[DanEC]

It may depend on what transmission you are using and what the manufacturer recommends. IMO I would not use a roller pilot bearing on an older transmission (T-10 or Toploader) They have a ball bearing on the input shaft and the input shaft fit is far from precise - doesn't need a pilot bearing. And if you have ever seen a picture of what a failed pilot roller bearing does to an transmission input shaft - it's not pretty - you would not want to run one. I would run a bronze bushing (magnet won't stick to it).

A roller pilot bearing does require closer tolerances on centering the bell housing. However, seems I've read that Tremec does require a roller pilot bearing.