Subject: Re: G9 gearbox
Adam, do you have the latest Club 4.5 litre handbook ? There is quite a lot of detail about the G9 gearbox in there by David Hine - page 93 - including seal info.
When I rebuilt my G9 a few years ago (before David Hine had produced the revised handbook !) all the seals (and bearings) in modern form were available virtually off the shelf from my local bearing supplier.
I hope this helps.