I have one that i built in the summer of 1983... i don't have any pictures taken of its internals...
a few recommendations:
1) it is currently made by "Harbor Models", they have hardware kits for motors, propshafts and propellers.
https://www.harbormodels.com/har1015.htmlthey are basically the only company that will give you the proper advice on hardware
2) i would not recommend buying anything from dumas... their motors are way overpriced for what you get, and their gearboxes are extremely noisy and difficult to build/install.
3) mine was rebuilt a few years ago and now runs on big slow brushless motors using belt drive reduction units. 99% of the people who i have spoken to that own Mr. Darby boats stare at me when i tell tham that like i have something stuck in my teeth, so i might not be the most appropriate person to talk to about runninng hardware (see #1 above)