Weights of components
Oh....if it fell..so what? It's a well-used engine and nothing underneath it.
But really....if you look at the strength of a single 5/16-18 bolt, then multiply it over 4 well-spaced holes, you'll see it's plenty strong. All the thread are in good shape. It's only 162 lbs per bolt...that's less than most women weigh. I can't imagine Bertha being picked up by a 5/16 bolt and causing it to break.
I've been at the scrapyard and seen the crane operators lift entire cast iron V8's with all the accessories, and auto trans, using a chain attached to a single 5/16 bolt screwed into the aluminum alternator. And they were jerking it around...no easy lifting.
Disasters only happen when you care about what you're lifting lol.