Acme Automotive
Check out this link. I think they may have what you are in need of.
I've had problems checking and inflating the rear duels until I found the straight end for the inner, and the angled for the outer. I have not got extenders, have only had my service tech install a brass stem on each tire. (not long ones or angled, either.
I can check all six tires and top off with air in about 5 minutes.