Hi Cub enthusiasts and experts. I have owned several J-3 Cubs over the past 30 years but never a PA-18. I am a Super Cub "believer" and have followed the evolution, mods & even the rise of Cub Crafters. One thing I have not come upon, nor have I researched to any extent, is the history of the PA-18 fuselage. In particular, what material (steel) was usesd in the construction of early fuselages? And did Piper end up with 4130 before production came to an end?