H.O. or not H.O.
 

I have an intake off a 87 merc cougar that looks like the H.O one but is there any stampings to tell for sure.

As well I have a set of heads off the same 87 cougar is there special castings marks to denote E7's vs E6's...

Thanks

The heads are E6's and the intake is non HO. To check you can see an HO stamped on the upper intake under the place where the plate bolts on if it is an HO. On the low output intake, there is no stamp. On the heads there is a four character part number on the under side of the head in between two intake ports. It will say E6 or E7 and then two letters.