There is a supplementary manual that you should get (if you can find one). Covers lots of stuff related to the loader, oil clutch, etc. but nothing to do with the transmission.
The 855 12A transmission information is in the D4 6U and 7U manual..
I need to replace the bearing on my input shaft. Can I do it from the clutch side or do I need to remove shaft from transmission?
Follow the service manual, transmission input shaft and bearing can be removed from the clutch side.
Thank you old magnet, that's a stress reliever.