I don't know the answer to your question, but I do know the answer to the next one..... the one about replacement batteries.
Check first with a tape measure and online to see if the battery box will fit a standard car battery. Most cars use Group 24 size. If it will fit, get a car or marine battery to replace the tractor battery. Any group 24 or similar car battery will have adequate Cold Cranking Amps and reserve capacity. Check to make sure that the terminals fit your battery cable. Group 24F has reversed polarity terminals.
If you can convince yourself to part with a little more money to get an AGM instead of a traditional wet cell battery then you'll never have to clean battery terminals or deal with corrosion and it will also last longer.
A standard alternator charging system will charge either type battery just fine.
rScotty