Which transmission bearings fail first

[DennisWaller]

I plan to replace all the seals in the 5 speed manual transmission on my 1991 Honda Civic DX which has 240K miles. My plan is to make those repairs and replacements that will enable me to drive an additional 200K miles. Although the transmission is quiet and shows no indication of excessive wear (no noise, difficulty shifting or jumping out of gear) and both the synchronizers and gears do not exhibit much wear a friend suggested I should replace some of the ball bearings. This leads to two questions

1) In your experience which bearings are likely to fail on this transmission?
2) Are there any significant quality differences between the OEM bearings that are made in Japan and bearings amde in the US by Timken, BAC etc?
Dennis Waller