Electric is a huge plus in simplicity and reliability. For what its worth with simple mechanical skills you can visit local junk yard and order the gear and nose and have less than $200 in the project - at least on the east coast lots of those easily rebuildable MT42 starters in scrap yards. Bob

Not going to be all that easy to find a used starter with the 1M0023 adapter. It would have to come off a D333a or D330a engine that had original factory direct electric start and would come with straight cut drive gear. There are some adapters listed on Machinery Trader but a bit pricey.
The original starter would be a 40MT. A complete after market starter replacement is a 42MT part # 10478998 and you would still need to change the drive to helical gear and get the adapter.

Off Road in Tn. shows two 1M0023. I was thinking of a setup like my D2 or friends older D6 not side mount. pony.