As Ed said the OEM fans are generally less expensive on the used market and may actually move more air than a 16" single bladed one such as a Spal, however they are generally intended for the lean burning emissions oriented OEM applications and more times than not were designed for OEM applications requiring them to contend with an A/C condensor or Automatic trans cooler in front of the radiator that is giving off huge amounts of heat. Generally speaking a well installed 16" (as pictured below) puller will be more than enough for what you need or want, plus the installation will be cleaner and lighter and pull less power thus allowing a smaller alternator. Like it or not it takes HP to spin large alternators. The hole on the lower portion of the RH tank is for the VW sourced fan switch that controls the fan relay.
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