300 Series gas cars should have 2 electric fans completely visible in FRONT of the radiator seen when the hood is up. Mine has these and also a standard engine driven fan as well. I don't know about the diesel, but since diesels typically run cooler than gas engines, if it has a fan off the engine or another fan somehwere else, you should be fine.

__________________
________________________
2002 Mercedes-Benz E320 4Matic
1995 Mercedes-Benz E320 Wagon
2005 Land Rover LR3 V8 SE
1999 Audi A8 4.2L quattro