Yep. Colin Seeley was buying Shaftleitner gearboxes for his sidecars in the early '60s. He liked them so well that in 1967 he became the UK importer of the 5 and 6 speed Shaftleitners. He offered them as an option on the Seeley G50 Matchless racers he was building at the time. If I recall correctly, when I started racing a Commando PR in 1972 you could still buy a new Shaftleitner 6-speed, but I never knew anyone who used one. We mostly used Quaife 5-speeds. Somewhere in the middle '70s the design was taken over by Ray Petty, and later sold to the Summerfield brothers, who still manufacture it as the PGT. I'm not sure where the change from importing the gearboxes from Shaftleitner to manufacturing them as Petty gearboxes took place. Maybe someone on the list can add some more detail.
Nova describe their gearbox as being based on the Shaftleitner design, but not an exact copy. That's all I know about it. Again, maybe someone here on the list can add info.
My understanding was also that the TTI is a much more robust gearbox. That's why I brought up the question when Alan said they were similar. Back when I was racing 920 Commando engine bikes I would have been at the head of the line for a TTI gearbox, but that was before their time.
Ken