Check out the @TxDon thread on upgrading his '66 Monaco wagon to a Sanden and related parts. It was a factory dual a/c car.
Only factory add-on systems were for just the front system, not adding the dual system to an existing factory a/c car.
As for the fan motor, check the factory service...
Very little historical info from Chrysler. Not like other brands. Have tried to find out how many were Gold and black, maroon and white etc. no info anywhere.