The 211 model of the Huey was called the Huey Tug and was designed for sling loading 105mm artillery pieces with an A-22 bag of ammo. It used a Chinook engine....and a unique set of 48 foot blades with swept tips. I recall seeing some video of them flying but do not know what ever became of them. They were designed to take 6000 pounds on the cargo hook.
Take a wander over to a Bell 212 or 412 sometime and look at the tailboom baggage compartment door hinges.....Bell 47 Part numbers on them. Just a bit of trivia.