Used Volvo Penta 1000531 aka 531 head, without camshaft.  This is the correct head for the AQ 125, 131, and 151 engines, and will work with other SOHC Penta four cylinder engines with carburetors.  

This is also a very desirable head for automotive performance engines, due to improved flow and better combustion chamber design.  If used in a turbo motor, replacement of the exhaust valves with an appropriate type is recommended. Does not have holes for use with K-Jetronic fuel injection.

This head has typical signs of marine use, mostly the expected wear around the #4 exhaust port.  Some reconditioning will be required prior to use.