I bought a Vintage Air unit here a little while back. It's pretty slick unit that uses the original control ac/heater control. I unpacked it when it came to ohhh and ahhh over it then I packed it back up.
One of the board vendors matched an online price that I found w/free shipping. I believe that all of the brands are pretty comparable in performance and price.
There are a few members who just installed the Gen IV unit that I have. Check out Crash_OK's build here in the 4x4 section and also HartRod's Suburban build.
Here's Mark's build. Page 13 post #311 shows the unit installed
http://67-72chevytrucks.com/vboard/s...d.php?t=494599
The Superburb. Last page post #1258
http://67-72chevytrucks.com/vboard/s...d.php?t=200387
Edit: The vendor was Scott's Hot Rods