I found these dc motors on Amazon as an economical replacement for the Skorpion's dreaded OEMs.
ICQUANZX Permanent Magnet Motors,31ZY 12V 8000RPM High Speed CW/CCW Permanent Magnet DC Motor for DIY Generator Mainly Used for Electric Fan Ventilation Mechanism, Heater.(12V8000R)
They were a direct fit and I've been running them since July here in sunny Florida. So far no complaints, though they have not been subjected to heavy rain. And to be honest, I use water wetter in the coolant and the fans seldom ever kick on as a result.