Part is mentioned in the manual for the Beetle until 1952 and the Barndoor parts manual untill 1954.
This MANN fuel filter is commonly seen on Porsche 356 Pre A engines.
Tuners like Denzel and Okrasa also used these on there engines.
Numbers as seen on the lid are: BF329 & KD 08.49
MANN Aircleaner used on industrial engines.