Interesting stuff thanks!.
I never thought that odo's and speedo's could read differently like that!. Im not sure if mine can still though as the speedo is fed by one cable... will have to check. If read 5% over from the factory and a previous owner slowed it down - its not impossible that they could of slowed the odo down so it reads less miles.... will have to drive it pre measured distances and check!.
EDIT, seen as my post count allows:
(the lights are white... not blue)