It is by pure luck that my old Palm Treo 755P vent mount works perfectly for my Sprint Touch Pro 2. It works so well that I even got the second one to be used on family van.
The mount I got is from here:
http://www.arkon.com/Palm_Treo_Mount.php
with the model # PTM129-S. The page is even updated to say it is compatible with TP2 now.
Hope you find it useful for you.
Lyre