Another filter question

[wal1809]

I bought a box of Detroit filters (To be exact Detroit Diesel fuel filter/twist and drain with a part number 23535985.  I took a chance and bought them for around $20 and they are still in the shrink wrap.

My question is if they are primary or secondary filters.  I have been searching that number and only found one site with very little information.  It was a filter cross reference website and they described it as Primary.

Any thoughts or knowledge given is greatly appreciated and I thank you in advance.  W

[Charley Davidson]

The threads on them should tell you, I forget which way but one is larger than the other if my memory serves me right.

[luvrbus]

Wayne that is a primary fuel/water separator filter should have a petcock on the bottom to drain water,same as a Napa 3418 filter

good luck