Most aftermarket lifters have a hole in the push-rod seat.
From 1953-62 original Chev lifters did not have a hole in the push-rod seat,1950-52 did.
Both types are fine.
I prefer the type with a hole in the seat. I cut a groove across the bottom of the push-rod, This allows trapped air to escape,(1950-52 push-rods came from the factory this way).
See pic.This prevents high speed lifter noise.
