Lifter galley sleeve

I've got a 340 block I bought some time ago and somehow I never noticed it before but it has a copper sleeve or tube inserted in the passenger side lifter galley that runs the full length of the block. I've never seen this before. Can anyone tell me why someone would do this?

Just a SB oiling trick.. very common... forgot to say its for roller lifters

Mopar sold the kit to do that mod.