Help identifying G50 gearbox spec from an unusual code?

[RichardJ]

Hi, I've just bought an G50 gearbox, but two things are making it difficult to work out exactly what spec it is. Firstly, the 'G50/XX' part of its code is scraped off (it has been lying around an a workshop for 20 years due to a broken clutch release shaft boss, no doubt having been dragged along the floor, with the 'G50/xx' part being the lowest point). From the fact that it has the longer bell housing for the rubber centred clutch disc and has the short nose cone, I believe it to be a G50/00 from an '87 3.2. It appears to have a limited slip diff.

I've tried looking up the 2nd half of the gearbox code in the '87 - '89 parts catalogue, but the format does not match. I also looked at later parts catalogues just in case it is not a G50/00, to see if they used any similar part format for the 2nd part, but they do not. The catalogue shows all the G50/00 model all having theformat 73H (or 74H) followed by the 5 digit serial number. However, mine has the format 12/ followed by the 5 digit serial number. After much Googling, I only found one reference to a similar gearbox code with the '12/'. It suggested it was probably a replacement gearbox. This would seem to make sense, as the letter is the model year code, and not having a year code on a replacement 'box seems sensible. Has anyone come across this before, and know how to decode the '12/' part? Any help is much appreciated. Thank you,

[RichardJ]

I'm answering my own question here, but maybe the info will be of use to someone else. It does have a limited slip diff.
I also counted the number of input shaft turns relative to one diff turn in each gear, and compared the results to the standard ratios for a G50/00. This confirms that my weird numbered 'box does have standard gearing.