I had an interesting experience this week that confirmed what Frank said above.
I wanted to order a new starter for my 1956 Johnson 30 HP RDE18. Originally the 1956 RDE18 came with a 6V starter. The old starter is Autolite MDH4001M. Distance between the mounting screws on the starter is 2 1/4 inch center to center. I have 3 of the matching bronze colored brackets. They match the 2 1/4 inch bolt spacing. I looked on Ebay at Total Power Parts and called them about their item 5270. According to their info on Ebay that is replacement for the MDH4001 starter. The person who assisted me checked their own screen data and it appeared to say that the bolt spacing was 2 1/4 inch.
Received the starter yesterday. You guessed it. The spacing on the starter was close to 2 1/2 inch. I also have one other bracket. It is painted white, It was on an RDE18 and had a bad starter . Stamped onto that starter is Autolite MDO4002M 12V. I put the new starter on the white bracket and the starter engages the flywheel and spins the motor over just fine.
The starter was $55 and is from Taiwan. No other identification. Because of fumble fingers I wound up removing the end cap. The inside looks like decent quality construction, nice commutator and good setup for brushes which look easy to replace.
The white bracket has two sets of starter mounting holes, the tapped ones about 2 1/2 inches apart and two others not tapped that look to be 2 1/4 inch apart.
So I think 6V starters have mounting screws 2 1/4 inch apart and are labelled MDH4001. 12V starters have mounting screws about 2 1/2 inch apart and are MDH4002 and are labelled with 12V. I think the white bracket was originally from a 1957 or 1958 35 HP as it has a shroud pin.
I still wish I could get a starter 6V or 12V with 2 1/4 inch spacing to use in the bronze colored brackets. Does anyone know a source?
