Stock 318 with a new noise.

If you have a thermal clutch fan, check that clutch too. A bad clutch will allow the fan to wobble, might make a similar noise, and take out the water pump too. Years ago my cousin replaced the water pump on his 350 chevy work van twice before he figured out that the fan clutch was the culprit. Well, he didn't exactly figure it out. Autozone was replacing the water pump under their warranty. The parts clerk there said, "I'll bet you have a bad fan causing this". he was correct.