Head differences?

[firekiller]

Can someone show me or explain the differences in the exhaust sides (namely the stud locations) of a pre-85 head and a 85-90 or so head? 

Thanks

Tico

[Marlin]

Back in '75 when the 20R was released, it had a total of 7 exhaust studs with only one stud in the center between #2 and #3 cylinders.
Due to the added heat from smog crap and additional horsepower, an additional stud was added in '85.
I also recall finding a lot of '75-'84 exhaust manifolds becoming loose.

I have installed the later 8 stud manifolds on the earlier head by drilling the manifold for the center exhaust stud.

[firekiller]

Thanks Marlin for the info.  Can you possibly post a pic of the area of the manifold that needs to be drilled?  I'm too much a visual aid person.  This would help out a bunch. 

Thanks again.

Tico
to marlin