G.M.you must know or remember that Skip had some issues with oil leaking pumps a few years ago and it was not because of oil viscosity. Mine leaked extremely bad from the startup on my new engine ,so bad I was afraid it was from the crankshaft front seal.I was relieved to trace the puddle to the pumps. I was the guy who sent the pumps back to Skip and they were stolen from his mail box supposedly. I did get replacement pumps and no oil leaks in last 5 years. If I had to do it over again I still would go with Skip pumps and on a 59AB I would not want a ball bearing pump but go with a bushing,engine oil lube pump,I have my reasons and expiereince with ball bearings and water or coolant.