Speedo replacement/OD installation

[Anthony Rayner <A.Rayner@mailbox.uq.oz.au>]

Hi everyone, Just a quick question....when changing a 1965 MGB mark I 3
synchro (5 bearing) standard tranny over to an overdrive unit (3 synchro)
you have to do a number of things...one of which is to change over the
speedometer and cable length.  Do you have to remove the old speedo and
replace with the new or can you recalibrate the old speedometerto handle
the change?  I hope so! 
Thanks...Tony Rayner.   charayne@dingo.uq.oz.au