MCI manufactures certain standard body styles for decades at a time. With just modifying a front or rear fiberglass cap, you now can make an 80's model bus look like a 2000 model bus. 

We offer a special rear cap to accommodate the new Rear Cap A/C system
which is almost 5 tons of air conditioning on a back shelf inside this rear cap. 

By using this rear cap method, your air conditioning is now in an area least used. It's not visible from the top like the old rooftops, and it doesn't tie up your basement, like the basement units.