That is correct sir! Although most people chucked that ducting because it either A) fell off anyway, or B) Rotted to the point that you couldn't attach it at either end, or C) the flange on the exhaust manifold rotted away.
Or the Thermac motor would not work after time.
It was really kind of simplistic in the way it worked, just the parts didn't hold up real well. Most people that took the ducting off never noticed a real difference in how quick the car warmed up anyway because, let's face it, nobody took off down the road until the car was warm enough to run on it's own regardless. Now, or course, that's all regulated by the ECM and you won't see any funky hoses like that on new cars. I'm sometimes amazed at the amount of crap GM put on cars from the mid 70's until the 90's that made no difference.