GU locks are now manufactured with a new style centre case
These GU locks feature rollers outside of the hooks. This is the wide lock version with a split spindle operation but it is also available in lift lever and narrow versions.
The main difference between the old and new style is the distance between the latch and the deadbolt, this will sometimes cause problems with strike plates
The other major difference in the height of the lockcase, although this shouldn’t cause any real problems when retro fitting