GT6/Spit overdrive

["Terry & Cindy O'Beirne" <esp@hypermax.net.au>]

Hi all, 
does nayone have expereinces with the overdrive mainshafts made up by 
John Kipping in the UK??

They regrind english marina 4 speed units to make up an all syncro J 
type or D type mainshaft.

Can anyone help with a 3 rail o/ d adaptor or the isolation switch 
mechanism off the selector housing

Thanks 

Terry O'Beirne GT6racer etc etc