I second this, I changed mine in Dec (it was cold with no working fan in my case. You can mostly stay work on a highway drive however). Fortunately it doesn't take but 30 minutes on an E53 (the Xoutpost links, info & photographs are enough). You don't need to remove the glove box. A good trouble light will help.

The original OEM part was made by Valeo and is sometimes co-branded with other mfr's. If you have a 10+ year old one, it's all metal.

A current, new correct / genuine BMW one is marked Valeo/Sitronic and is made in Germany. Plastic base (the mounting / plug end) and metal heat sink. They also have date codes, a good want to also confirm that you have a new part.

There are some unknown origin parts on Ebay. Buy new and genuine for this, believe me you don't want it to fail in winter (I and other friends have experienced this). For those in a hot place, I suppose no fan in blazing heat would be equally less pleasant.