This is one of the mythical Triumph 5 speed gearboxes, predating the later 77mm 5 speed that appeared in the TR7, Rover SD1, etc.
Looking like a normal Triumph saloon, TR 4-6 alloy gearbox with a bit tacked on the back, this is essentially what it is! Ours is numbered EX5SPD/1 (experimental 5 speed number 1), I know of another in Germany, and there was supposed to be another in a big saloon somewhere up North? Ray Henderson once told me on one of his visits here that 'it wern't nought to do with us' (Triumph)! He later rang me up and appologised, he had spoken to Triumphs chief gearbox guy at the time who had confirmed the project had indeed happened, prompted by the intervention of a certain Mr Kas Kastner. All the ones I have seen or heard of have had saloon input shafts, and have at one time or another been fitted in saloons, not TR's, unless anyone knows differantly? Why didn't they go into production with this instead of the incredibly heavy cast iron case, clunky old 77mm box I will never know?