I was on the fence. The 5/16 would be in aluminum. Yes, 4 as compared to 2. But the (2) 3/8 were grade 8, in iron, threaded as deeply as I could.
I couldn't find anything except tensile strength, of course, I was looking for "pull out" strength. I don't even know the correct term, probably why I couldn't find info.
I should have posted this question several days before I did it. I would've collected more opinions. When I got up yesterday, I said, "Today it goes in". I wouldn't have been disappointed if I couldn't do it, giving myself and 2 friends such short notice.
And, as I said, I probably did it years ago. Got CRS now. lol