engine build ?,lifter oil galley tube install
The block gets drilled from both sides and the tube gets inserted in with some hammer help. You'll need a peen tool to clearance the lifters. The lifters will not go into there bore with the tube until you use the peen tool.
The peen tool is in a basic description, a long metal rod that gets put into the lifter bore and hammered downwards in order to bend the installed tube so theres room for the lifter.
Did I help or was that confusing?
MoPars Engine books has instructions for this.