Fuel / Water seperator filter

[Joker2]

I'm just installing a whole new fuel system ( except tanks ) to a freshly rebuilt 94' Johnson 150. Installed the Stainless water seperator bracket, looking through my Jamestown boatbuilding cat. trying to choose the right spin on filter. 2 questions :

1. read somewhere that the 10 mic filter is for newer motors with higher pressure fuel injection and the 21 mic is for the older motors. asked a local marine mechanic and he said everything is 10 mic. ( not crazy about this guy in the past ) Does it matter ?

2. Looking the filters up in my Jamestown Cat. a little confusing, most of the Sierra filters and Raycors say they are for Yamaha and Merc, how do I know which one to choose ?