If you look in the back of the GK manual, you will see what the heater box on the top of the engine looks like. From there it is simply a matter of running a flexible duct up to the back of the cab to the blower and the underseat outlet.
I have a blower but it is rough and i would never use it anyway because it draws air from the engine compartment. I would be afraid of drawing in exhaust fumes. If you have any interest let me know. I know its been a long time since this post started. Also, i need to remove the cab to get the heater out. Funny design.