that you reference is a light guage metal structure that appears to gain its strength from its shape more than its mass. we often lift the cars by it although it is probably best not to. if lifted without any wood on the floor jack it can knock off t he undercoating and dent the member. this could easily lead to rust. i think if this is the only place you find rust that it may well be fairly easily repaired.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.