Recreating MP Viscous Fan Kit

Many clutch fans will fit. There may have only been two diameters for water pump shafts since some fan clutches I've bought have a spacer ring for different applications. I recall my Mopars don't use the spacer, so perhaps Fords did. I recall that Chevy water pumps have 3 bolts so wouldn't work. I can mount the very short fan-clutch for my 1985 M-B diesel engine on my Mopar water pump (same w.p. shaft diameter and slots for the bolts). Those are so short you must use an open-end wrench on the 4 bolts. The fan-clutch for a ~1980's Jaguar is also said to fit and also short. The M-B fan is nylon so less concern of it cracking and losing a blade. There was an earlier aluminum fan (did crack), so people prefer the later nylon fan. The uneven spacing of fan blades appears common and I think is done to avoid resonances.