Did the 1973 Cuda 340 have a clutch on the radiator cooling fan 
Yes...
My '73 Cuda (340) came from the factory with a clutch fan.
All 340 fans for 1973 had 7 blades.
All 340 fans for 1973 were 18.5 inches in diameter
All 340 fans for 1973 were 2.5 inches in width.
The above numbers are from my 1973 chassis/service manual
1973 - 318 engines had 4, 5 and 7 blade fans depending on the transmission (standard or automatic) and if it had A/C.
I replaced my thermo fan clutch six years ago. It cost $60 from a local auto parts store. My original clutch drive quit working causing my engine to run hot especially at low speeds and at an idle.
