Rare Dodge Dart GT? Which engine is this?

George Jets said

This is interesting.

Take a look at the lower radiator hose looping under the crankshaft from the passenger side, then back up to the early cast iron water pump outlet on the drivers side.

Not sure, maybe they needed that cast iron water pump casting so they could mount the Alternator on the driver's side?

View attachment 1716042071

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The cast iron water pump is so the fan won't hit the radiator. I tried to put a new aluminum water pump in a 66 Barracuda and even with the stock 4 blade fan there was only about 1/4" (slightly less) clearance between the back of the radiator and the fan blades. Too close for my comfort so I put the cast iron pump back on.