I learned about the snap-ring groove for the lifters the hard way. I was changing two cylinders for a customer, one on each side. setting up to reinstall the lt cylinder I was carefully turning the engine when I heard a "chink" sound from the rt side. Investigating I found that the pushrod cup had come out when I pulled the push rod out because it didn't have a snap ring (old style) as I turned the engine that cup cocked side ways in the lifter body ,caught on the case and broke the side off the lifter body . He was very gracious and I got to provide a disassemble reassemble for free. Brian
I was changing two cylinders for a customer, one on each side. setting up to reinstall the lt cylinder I was carefully turning the engine when I heard a "chink" sound from the rt side. Investigating I found that the pushrod cup had come out when I pulled the push rod out because it didn't have a snap ring (old style) as I turned the engine that cup cocked side ways in the lifter body ,caught on the case and broke the side off the lifter body 
. He was very gracious and I got to provide a disassemble reassemble for free. 
Brian