Stock 49, that film completely explains the rod oiling system. The only question for me is why anyone would go to the trouble of oil jets and dippers when all you have to do is drill the crank,a very easy job at the factory IMHO compaired to all that plumbing!
A question that can only be answered by some long since dead engineers from 1930's GM . . . or perhaps the accountants from the same time period.
Transferring oil pressure from the mains to the rods involves so called 'rifle' drilling from the crank journals to the rod bearings . . . this must have been more expensive then the plumbing . . .
For me I am just working with what GM delivered at that time . . .
