I built and am flying George Aldrich's MAN August 1966 Texas A&M NACA Duster. It is a semi scale rendition of the first purpose built crop-duster that later led to the PA-25 Pawnee.
Mine is powered by an OS 40 FP from Ebay with composite Xoar 11/5 and weighs 48 oz. George's had an Ed Southwick McCoy 40 and weighed 59 oz. I have almost 50 flights on mine with no trim changes so far. Superb stunt machine.
Tom McClain