Re: Engine year?
NO need to head off to all kinds of other sites, just post your SN here. A number of people can tell you what it is and all sorts of info.
You can also go the the Mercruiser site and locate Parts express. Use your SN there, and you can get the EXACT part number and part if you want to order it.
Just noticed you already posted your SN..... It is an 85 motor.
Go to Parts Express and get the updated PN for the manifold. Is the manifold you ordered and OEM, or some aftermarket manifold that may not fit, but is a lot less expensive?