Shop manual for 2005 Santa Fe 3.5L shows a fuel pump filter in the tank & a standard cylindrical fuel filter outside the tank. Manual states change the "fuel filter" at 45000 mi. Can't find outside filter & tank must be drained & dropped for "fuel pump filter". Which one to change?

You don't have filter outside. The filter is in the tank. Yes the filter can be service after you remove the furl pump, disassemble the pump and replace the filter and the strainer. Is important to replace the filter just like any other filter.

Change to Exterior filter not the tank filter. The in tank filter is actually a sock located on the Fuel Pump in the tank. This is rarely a problem. The exterior filter is going to be in-line most likely on the passenger side of the vehicle toward the rear. Easiest way to locate it is to trace the fuel lines back tot eh front of the vehicle from the fuel tank.