lifter galley crossover tube

The trick with Mopars is the oiling for the main bearings, and ultimately the rods they feed. That's because the pass side lifter galley gets pressurized oil first. Then it's redirected down to the main bearings but it has to make a sharp turn for each main feed. A separate passage runs oil to the drivers side galley at the #1 cam bearing where all it feeds is the lifters on that side. When you factor in the oil pressure bleed off from the 8 drivers lifters, and the 6 pass side lifters forward of the #4 intersection, plus the amount of oil leakage that larger race clearances in the lower end provide, the velocity of the oil within that pass side, and especially at the #4 main junction, is very high. The faster the velocity, the less willing and able the oil is to slow and make that turn. So the theory goes that by tapping the oil from the #4 area, the localized speed at that turn is lowered. A convenient place to dump velocity is the drivers side galley because there's a lot less flow there already. It's not directing slow oil "to" the #4 turn, it's adding volume thereby slowing velocity "from" the #4 turn, and dumping the oil into the drivers side. That's why the angle of the holes you drill, and the shape of the fittings is so critical. If it's not just right, there's little effectiveness to it.
It's on the Guitar Jones list of mods to do but I posted on that thread saying it was a waste in all but the highest revving road race type builds. Modern oil control theory, better bearing choices, and tighter machining tolerances go a very long way to fixing the starvation issue unless you're spinning 7K+ for extended periods of time.