Need some advice on material selection

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John U.
Here is a pic of the intended Upper and Lower Bushings. Pretty straight forward with steel inner sleeves, Poly bushing and D.O.M. Tube outers.

JP,
7ga. is 3/16ths. I am concerned with hole elongation if the fasteners loosen up but, now that I think about it, the fasteners are never going to loosen up because I am going to be so freakin' paranoid about this whole suspension that I'll be checking it every time I hit a hard bump...
I'll be milling the bolt holes to just slip the thread at assembly so I think I will go with the 1018 and just keep my eye on it...

Thanks guys. Just thinking and talking it through with you solves a lot of problems in my mind.
Mark