Now you tell us, it would have been nice to know this a bit sooner.
Anyway, installed 2.5OB, re-downloaded Normandy and NTTR and uninstalled Alpha (as nothing copied from it because it was on another drive) and all is good.
Question
When the release build to 2.5 update is available, will Normandy and NTTR be copied from 2.5OB even though this is on another drive?