Great post! Thank you. Regarding your question re: replaced Approved hub, the only explanation I can come up with other than a replacement would be that the Tiger was a slightly cheaper bike than either the Corvette or the Jag and the plant was still trying to mount the SA hubs on the higher dollar bikes (????).
Both of your bikes appear to have SA triggers. Going back to an earlier question, have you found any 3-sp. 50s middleweights with any kind of shifter other than SA?
Oh, going back to your question about the trigger cable on my Tiger, I believe it should have been ribbed grey but considering the existence of the Approved hub, I'll freely admit that I haven't got any idea. It's buried right now but when I dig it out, I'll try to remember that you raised that very good question.
Best regards,
Kit