The only reason you'd have to go to a different grade would be to go
Grade 5 but in a larger diameter to get a greater yield strength and
material that is more malleable. It's extreme overkill though.
The ears actually snap off the steering box first before the bolts fail.
As the drill sergeant said, "I taught you everything you know. I didn't teach you everything I know."
"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so."
- Douglas Adams