I'm stumped. I don't have the expertise to figure out an acceptable substitution for a rudder tube. The plans call for 2" X .059 wall, 2024 T3 aluminum tube. I'm not having luck finding that size in that wall thickness, so I wondered if 6061 T6 with a larger wall thickness would work instead. 6061 is a lot weaker according to the spec sheets, so how thick would I have to go to get comparable strength to the 2024 .059? I could go thicker wall in the 2024, but that gets real expensive, quickly. Why do designers spec out a difficult to find material in the first place?