RayMich:
The tank is made by KSH Marine out of Lake Havasu City, AZ.
I have the dimensions here somewhere I have to look for them. They do sell premade tanks of various shapes and sizes if you don't need one custom made.
This is pretty much the install although I didn't purchase my tank from here.
http://www.auxtank.com/auxtank/installSteps.asp?step=1
Yes it has several baffles installed inside the tank. I'm using a transfer switch, I don't like the idea of a gravity fed set up.
I have a switch mounted in the cab, flip the switch one way the truck uses the stock tank and stock fuel gauge, flip the switch the other way the truck uses the aux tank and stock gauge.