Bolting on rear A-Body trailing arms?

[Tom.A]

Hello,

Sorry if posted before, but could not find a thread related. I will be putting my rear suspension on my frame soon. Application is a 69 Chevelle with a 9" Currie, Currie adjustable upper arms and Speed tech lower trailing arms. My question is do I use the OEM bolting with thread sealant or should I go with Grade 8 fasteners or ?. What are some of you guy's doing? I am concerned with using original or even reproduction because it is likely worse metallurgy. I feel there is allot of stress in the load and deflection with A-body four link system. Any comments would be great.

Thanks,
Tom