[wpayne]

I think transient put it very well. I too *think* that if the component can be engineered efficiently in a way that the structural rigidity/shape/etc is not compromised or where the component is not be pushed pass it's stress limit(like the tower bar) with it's given use, then go with aluminum. Have the advantage of it being lighter too.

If what you need is strength or where aluinum just won't do, go with steel(stainless of course).

edit: Then again, I gues there are sometimes(can't think of one now) where you need a little flex, a little give, to absorb some of the stress. I guess thats why you use steel when you need more strength. Okay, nevermind.