John,
1) You will remove the front bumper cover or at least slide it off far enough to remove the fan left trim, fan right trim, fan bottom trim, fan grille, and slide the rest of the assembly down behind the crashbar and out of the truck. Here are the TIS procedures for YOUR 2005 3.0d.
BMW TIS
a) Go to repair manual, E53, 51 trim, Front Bumper, Removing and installing / replacing the lining of the front bumper (since 10/2003)
b) Go to repair manual, E53, 17 Cooling, Additional electrofan, Removing and installing / replacing auxiliary fan assembly (M62, M54, M57)
2. I purchased an OEM fan from Tischer BMW (getbmwparts.com) YOUR 2005 3.0d part number is
64546921382
getbmwparts.com sells this part for $464.06 but you may find it cheaper to purchase in Europe.