I have no experience with automatic transmissions, that is what a 700R4 is right?
If I ever own a truck with an automatic it is likely to be a new 6 speed Allison, because I like how they act, and adapt to driving habits and the load, and they are available with two overdrive gears. I am afraid of the price though, and cost of repairs and parts...
But for the most part I don't care for automatic transmissions, when manuals work so well, and cost less.
Most step vans are nearly 8' wide, and an AD Chevy truck is very narrow... So if I understood your question/possible plan? Then I don't think it's a good idea to put a step van tail on an AD truck.
A custom built box is probably going to look better, more professional at least.
Grigg
