Yes mine are chrome and they do use a lot of salt on the road here, I am in south east Idaho so it is the same as where you are. this is the first winter with the stacks on, but I don't think it will be any problem. I love mine. I went 5" but may go bigger if I ever get a lift kit. that is on my list for the future.

 

My stack came out of a exhaust shop's "blem" pile. Three years and no rust. Maybe mine is stainless?

 

Best bet is to go to an International dealer or Mack dealer. I believe my stack is mfg by Donaldson... I have had zero issue with it after 8 or 9 months