E39 - Air Flow Meter for 525 TDS Touring April 1997

Hi, I need to substitute the Air Flow Meter on my car. It's a E39 525 TDS Touring (April 1997). The current one is a PIERBURG, but iI cannot read its part number. I would like to avoid to stop the car and keep it blocked until I get the replacement, as I utilize my car every day. I would prefer to preorder the part and stop the car just for a few hours. So I was wondering if someone may tell me the exact code of the airflow, so that I can buy the replacement and get it substituted in a very short time. At last, I would prefer not to buy it at BMW, but I would like to order and buy it directly at a spare parts shop (either PIERBURG, BOSCH or whatsoever). The markup applied by BMW is unjustified in my opinion. Thanks for you inputs. Alberto