These Rockers arms from MMR have been modified to work with GT350 cylinder heads when used with factory 11-17 Mustang GT cams (stock or aftermarket).
A look at the picture below shows that what happens when they are not modified and camashaft to Rocker arm contact occurs.
This simple set of 32 rocker arms from MMR provide adequate clearance and are the only thing needed to run the 11-17 style cams in GT350 heads. A small radius has been added to the rocker arm, the amount of material removed is kept to a bare minimum to maintain strength.
WARNING! Factory GT350 rocker arms cannot be used with 2011-2017 Camshafts in GT350 heads, they will hold the valve open. You must use this roller rocker from MMR!
If you wish to use the Factory GT350 Rocker arms you must use custom camshafts with the same base circle as the GT350 cams!!