Ive read this at a unnamed site.I could tell you where, but then i would have to kill you.
* Unsurpassed Versatility - A Model 660 can operate up to 16 lamp feet with a total of 464 rated lamp watts.
* Individual lamps can be 2 through 6 feet each. This corresponds to 12 different lamp configurations. Maximum light output with VHO and HO lamps.
I dont think they make 72" retro reflectors ,instead i think you have to use two 36" and clip them together.