Replacing old sea strainers with new Stainless Marine so before I call Stainless .......Can someone explain why 4 inlets on each can?......not sure where to run hoses through top 2 or bottom 2?

Is there a screen in between the top fitting and the bottom one ? typically the input is the top and the output to the sea pump on the bottom, not sure on the 4 holer but you could plump in a fresh water flush in the other bottom connection and plug the other top fitting

2 inlets (upper), 2 outlets (lower). Gives multiple mounting options.

When Looking at the 2 side vertical inlets, the basket strainer only covers the bottom inlet, ............the top inlet is above the strainer basket on the inside........which inlet should the hose connect to that brings water from the outside pickup tube ?

So it makes no difference (upper or lower) any combination as long as one hose connects to inlet and the other one connects to the outlet?

Mine are connected to the top gravity feed to the lower fitting through the basket to the sea pump, this way any junk picked up sit on top of the basket