Water cooled exhaust manifold [marine use] for 240/300 - used

[1986F150Six]

I have never seen one before this:

https://www.ebay.com/itm/ECON-O-POWER-MARINE-WATER-COOLED-EXHAUST-MANIFOLD-FORD-240-300-CID-USED/223769830463?hash=item3419b8a43f:g:h0MAAOSwX-Zd3rZc

[Gary Lewis]

I haven't seen that one before, but it is normal for boats to have water-cooled exhaust manifolds.  However, that one channels #1 past #2 then #3, etc.  Looks seriously restrictive compared to an EFI pair.  And $1000???