Stainless steel pushrod tubes will not rust like factory tubes.
While we do sell stainless steel pushrod tubes, we actually recommend and use only stock pusrod tubes. You should put a light coat of black paint on them prior to installation to help with heat transfer anyway, so stainless steel is a waste of money. Just make sure to use a light coat of flat black, not the high temp stuff either. It tends to have a high clay or metalic content which will actually help to insulate the pushrod tubes and reduce the heat transfer.