Gearbox parts advice with o/d conversion

Roger K · May 3, 2021

Could I crave a little more advice, please?

Fitting an overdrive gearbox to my late MkIII GT6. A few questions:

1 - which speedo cable do I need? All I can find in the catalogues are lengths, which don't say what application goes with which cable. Looking in my factory parts book, there doesn't seem to be a different one for overdrive cars, so are they both the same - o/d and non-o/d?

2 - I have, in the pile of bits, an 'uprated' overdrive switch lever to sit on the end of the selector shaft and work the switch. This seems large and clunky, and I can't see an obvious way to fit it, although there is a threaded hole presumably for a lock screw. Is this worth fitting, or should I just stick to the standard bit of folded steel?

3 - Where should the Lucas 6RA relay for an overdrive car be mounted?

4 - I vaguely remember reading somewhere that the original right-angle speedo drive needs a washer behind it when mounting to the overdrive. Did I imagine that? The one that came fitted to the gearbox is clearly old, but has no washer between it and overdrive.

Thanks all!