2017 ram 2500 broken manifold bolts

Now my question is which bolts have the higher shear strength, a gr-2, gr-5 or gr-8?
On the subject of studs and nuts, the GM LS engines and the Ford Mod engines both use studs and they are both having the same cast iron exhaust manifold attachment breakage problems as the new Hemi that uses bolts.
Guys, please do not interpret me as an overly educated man, I have alway been just a hard working blue collar stiff. I learned everything I know in my 70 years through practical experience, and from asking questions and listening to those with experience.
Two qualities to discuss; tensile and shear.
As the bolt grade increases the tensile strength increases through chemistry and heat treatment. This increased tensile strength provides higher clamping load, but at a cost, Shear strength. A gr 8 bolt will break in shear while a gr 5 or gr 2 bolt will tend to bend.
Hope that clears that up some.