Instead dragging my AB 1600 and the Vagabound battery out for a mid day shoot, I am trying to figure out the best way to mount two Quantums on a light stand. I obviously need a cross bar that can mount two umbrella adaptors. Is there any contraption out there?

This should work
http://brewerbracket.com/el-doble-dual-flash-umbrella-bracket.html

May get one myself.

Or this:
http://www.bhphotovideo.com/c/product/90003-REG/Morris_32203_MTH_203_Umbrella_Tilt_Head.html

If your a DIY type, you can make one for a few dollars:

DIY Dual Flash Bracket

Or save time and spend money. I'm lazy and bought the Ziv Dual Flash Bracket:
Ziv Dual Flash Bracket

Al Jacobs Perfection Bracket

Photoflex Dual Bracket

Here's a couple of Norman LH2 heads on my DIY bracket (like an Al Jacobs) with CSRB bracket.

Hey, Scott, do you have a photo from the back so I can see the mounting?Also, what is the black rectangular box on the right of the photo?

the black box is a Paul Buff CSRB+ receiver.

http://www.alienbees.com/cybersyncplus.html

look halfway down the page

http://reallyrightstuff.com/flash/07.html