What do you want to know on the un90/91?
Fitted mine in 1992, came out a few years ago as it had a hint of play, still perfectly smooth.
Been through dossing around at nights urban style, paper rounds, big hills, rain, sleet mud, commuting, neglect, not used for a few years Ridden again then not used much and then back out in Retrobike land and retired etc...
Good bottom brackets.