It may have been the GT2 that had this type of rocker. I got info from a thread on Rennlist. Not totally clear but apparently there were both types were possibly used on the RSR and GT2.
https://rennlist.com/forums/porsche-cup-cars/745599-993-rsr-rocker-arms.html
I got the one I have from Chris Cervelli with a bunch of other parts.
john