OK I went hunting for the source of that leak. I found an a/c bracket bolt popped out and very loose. I did that water pump and as I tightened it down It felt like something you don't want to over-tighten.
Yeah GM stuff I got, tablets, is said to be like the bars stop leak I put in years ago to stop a heater core leak. Clogged the rad had it rodded out still may be clogged a bit.