Thanks to a couple of kind contributors I can add a lot of detail on the original Special tuning Limited slip differential, first is a copy of the original flier, thanks once again to Karsten. Just click on either of the images for a readable size copy.
Then we have a series of pictures of the actual article courtesy of a new contributor Ronnie Hermansson in Sweden.
This C-22G 421 LSD was particularly aggressive in operation and demanded a seriously firm grip on the wheel to avoid careering off the track or road! A modification that wasn't for the faint hearted.
As an interesting asside, all Homologated tuning parts had to be offered as "standard" options in one of the manufacturers primary markets. It was for this reason that if you bought a Mini Cooper S in South Africa during the 1960's you would be offered one of these by your motor salesman!