OD speedometer

[Mgbbob@aol.com]

Hi again listers,
Can anyone comment on the need for an overdrive speedometer for the D type 
conversion I'm about to make? If I left the old non overdrive speedometer in, 
would speed be grossly off? 

While they're not available though Moss, is it imperative that I search one 
out?  

Does anyone have the appropriate Smiths numbers for my 66 MGB? Does anyone 
have a spare speedometer they want to sell?
TIA, listers
Bob Stahlbush 
66 MGB GHN3L 78708
60 TR3A TS 81398L