727 clutch pack clearance

CudaFactHackJob said
You can install a rear clutch lower plate on the top of the front clutch to gain one extra plate. You have to twist the retainer to install it. I use .061 red eagle smooths in the front clutch to install even one more.

I thought the rear clutch lower plate was super thick with a ring protruding to push on the diaphragm/ spring...