You will very seldom see a "super single" on anything but a fuel hauler. The main reason they were designed was to save weight so they could haul a few gallons more on each load generally for more short haul.
We just did one of the low profile units here at FOK last week and it looks great. The cost was around $3500 installed. Give me a call for details> Jon Mosier 800-241-0138.
I have sold about 30 units with the MBE900-280&300hp & allison automatic. The reports I am getting back from owners I consider to be reliable is about 10MPG. Hope this helps.
JON
Another good place to have this kind of work done is Eddies Truck Repair in Knoxville,Tn. He has lots of experience with all kins of expediter work and is very reasonable when it comes to price. (865)546-2445.