I would say Rockwell, but I haven't seen one with the grease zerk in the center.
I went to the 'puck' style from Jet boat performance. Mine is a One piece rear main seal small block.
The puck has the 6 thru bolts to the crank, and a 4 bolt flange/yoke bolts to the puck. Then the double u-joint, to the pump yoke. Hope this makes sense.
Dan'l