T-Notch adapter sub-part.

So, I built an adapter for a friend to mount his [programmer to a Sirius car mount.](http://www.thingiverse.com/thing:561239) Later on, I bought a [Bracketron Vent Mount](http://www.kmart.com/braketron-grip-it-trade-vent-mount/p-05720019000P) and noticed it had the same little T-Notch mount to it. I figure there are probably more T-Notch gadgets out there, so I am publishing the T-Notch sub-part to stitch into your design.
It comes in both .stl format and .123d for Autodesk 123D Design.

**NEW**
I added the matching T-slot that the T-notch connects to. Add to your design. It's shown belly-up; attach the top side to the target, either recessed or not.
(work in progress)