If you look at the picture, this extension is not a Stenholm, I believe it's a Barnaby , it could be also a Fawcett(please correct me because I am interested in knowing for sure).
Brian Baty in Kitchener/Toronto has one on his bass if you want to try one out. PM me if you need contact info.
I used to have one on my old bass. They are really well designed and easy to use. I like how you could adjust the height of the levers. I replaced the spring mechanism with elastics from broccoli stalks for a smoother and quieter action (and it didn't catch on the inside of my bass case either!).
I think Rob Clutton might still have an old one in a drawer. I remember he had one on his awesome Prescott bass when I live in Toronto 18 years ago (eek!) but recent pictures of him I've seen on the net show his bass with a fingered extension. I'll send you a PM with his number.
