Correct treatment for critical suspension bolts?

[David Booth]

Hi all:

Seeing Tom's post on the 330 GTC suspension rebuild, I'm reminded that I wanted to be sure about the specs for certain suspension fasteners on my car.

On my Cab, the lever-action shocks connect to the rear axle or front suspension arm via a cast steel link, and ultimately, a bolt through the lower end of the link and through a pair of steel ears. One of them was rusted into the bushing and I had to cut it out. In another case, one of the spring mounting bolts is similarly frozen in its bushing in the spring eye and probably won't be salvageable.

The original bolts were mighty hard, but ultimately yielded to an air-driven cutoff tool.

Question is, what do I use in their place? A normal metric 10.9 steel bolt? A stainless bolt? Something case hardened?