I agree with Kevin. I rebuilt my pump in 1995 and first installed it about 8 years ago. I rebuilt it completely stock (except for the locking collar) and it hasn't leaked a drop in the 8 years I've been running it. Just be sure to add grease around the LEAD packing rings as you assemble it, then adjust the brass nut a couple times during the first few days of running. I haven't adjusted the nut since then and have only greased the rear bushing twice in the past 8 years. I also don't run my generator belt too tight. I also run 50% antifreeze, which helps to lubricate the thrust washer next to the impellor.
The pumps I've rebuilt since then I've been using the rear brass bushing with the double lip seal on the rear of the bushing, as shown in #1 of this post. This will help to keep any grease from entering the coolant. Pack grease in the V of the double lip seal when you install it.
Like Kevin, I've heard too many reports of bad bearings and leaking pumps that are claimed to be "leakless". I'm not sold on them, but then what do I know.......I still like generators and stock headlights over alternators and halogen bulbs!
