block identification

[birdy3897]

I have what looks to be a 1970's mercruiser 140 engine. The number off the block is 3937746. Anyone know how to find out what year this engine is? I also have serial numbers off the flywheel cover and valve cover. thanks

 

[Alumarine]

Re: block identification

Looks like a 72-78.

Mine is a 74 (I think) and starts with 377.

Someone might be able to help narrow it down but that range will help.