Was going to use straight one with 1/4" female threads but it put it too close to the window to allow much articulation.
https://www.amazon.com/gp/product/B009GLW1PG
This is the one I used that is angled.
https://www.amazon.com/gp/product/B0012TRIY4
They also have a straight one that offsets the ball.
https://www.amazon.com/gp/product/B0012TRIXU
Both of these are actually called a motorcycle base mount.
RAM mount for 6620 combine revisited (pic warning)
