I finally got it off. Some liberal use of PB Blaster and lots and smacking it with a hammer. Funny thing is there was almost nothing to clean off the block afterwards.They do spray that shit on the highways, and I think some town. The issue here is it's a high mile truck that I got pretty cheap and the previous owner did not take care of it the way I thought he did. So I am going through fixing stuff. The pump was likely on there for years. The reason for changing was really due to noise with the fan clutch. I figured if I'm gonna change that, I may as well do the water pump too. Found a seized idler pulley while I was in there so replaced the pullies too.