i have a 1928 Model AA Doodle Bug real nice condition its made out of 1928 AA has 4 speed transmission with place for PTO. It had speed reducer that was made for using a model A three speed car transmission that they used on the first 1927 AA Truck i did remove the reducer because it didn't fit the 4 speed. The pictures also show how i modified the drive shaft.
http://greenstore.org/Doodlebug.html