Sealed bearings inside a manual transmission?

[Headhunter38]

I'm in the process of tearing down my manual transmission from a 1987 4wd van. I noticed that both the input shaft and output shaft rear bearings are both sealed bearings. Apparently it's not completely uncommon as a Google search tells me that other people are asking about this for their transmissions. What I feel is more than coincidental is that both of these bearings are bad. The input shaft bearing I knew was bad because the transmission would whine in neutral and it would get quiet with the clutch depressed. I did not know the output shaft was bad until I took it apart.
My question is are these bearings supposed to be sealed by design or did someone use an incorrect bearing during a possible rebuild?
If this is by Toyota's design I'm thinking of replacing them without sealed bearings and or removing the seals from new ones. I can't see how a sealed bearing is any good inside a manual transmission. Especially considering the two that are sealed in this transmission are both bad.

[Jan-Willem]

I have no idea, but when I look up pictures of the original part numbers, some of the bearing do indeed look sealed, or at least shielded.
(toyota 90363-30059 and 90363-32024) so it might be original
https://toyota-usa.epc-data.com/van/...s/3305/33311A/