On my 1983 300d turbo, I have the 6-blade metal fan. I know they changed the design to the 11 blade plastic fan. Is there a big difference? Less drag? Quieter operation? Less susceptible to failure? Is having the original 6 blade metal fan a sought after part? Should I replace it? My car runs fine, doesn't overheat, but don't know if my engine needs it?

Thanks