Well Stu, that's the debate, isn't it! The GM engineers felt it beneficial to put a seal in the newer ones and then there was the earlier rear mains which used a slinger also but that was replaced with a proper seal eventually. I would say the slinger would take care of most of the lubricant but you will always have some sneaking past and over a period of time it probably will dirty things up a good bit.
I'm still not convinced that I shouldn't invest the hunert bucks in the modification. Spread out over the next thirty years that only amounts to a few bucks a year. (That's when they're gonna take my license and truck away from me cus I'll be to blind and senile to drive)
DG
