If the bolts are threading into cast iron, such as the steering box, a grade 8 bolt might not be a good idea. Tightening it enough to get the required "stretch" to keep it from loosening might overstress the threads in the box. Grade 5 might be a better choice. Nut and bolt connections are a different story, as long as the grade of the nut matches the bolt.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!