I agree with Brent, and an original pump is easy to rebuild. I rebuilt mine about 15 years ago and have been running it for the past ten years without leaking a single drop.
Last fall, after the vinegar rust removal treatment, I installed a rear bushing with the seal in the back of it. This will keep the grease and antifreeze from mixing with each other.
My old used temporary engine had an accumulation of rust in the rear of the block. After years of running many of the rust flakes came loose and plugged the radiator until coolant came out the overflow. I also installed a drier sock to trap any future rust that may be remaining, but I feel confident that 30 days of running pure white vinegar got rid of the rust.
