I have the MBS tapered bearings installed on my 54. To be honest, I'm less than pleased with the fitment. First off, I had to emery clothe the hub to get the races in, they were crazy tight. I then had to emery the spindle just to get them on. Not to mention, you can't drive the seals on all the way, and I had to use machine bushings behind them because I couldn't get any pre-load on them.
When I researched the Timken replacement a few years ago, finding something suitable for the inside bearing wasn't a problem. The outer bearing is the odd duck. It would need to be machined and threaded for a 3/4 nut.
Anyhow, If I were to do it all over again, OEM ball bearing all the way. They used these bearing on 3600-4100 trucks, and the 4400 were similar, seems to me they are up to snuff for just about anything.
