However I would also ask the question WHY ?. What is the benefit to change from a 6v system to a 12v system or 24 for that matter.
If its a starting problem , as they state, if the tractor is hard starting then changing to a 12 volt system is not fixing the problem but masking it. How long before it is hard to start at 12 v.
I would think the main advantage to the switch would be the availability and lower cost of 12V replacement parts along with the ability to add 12V accessories. I'm guessing that 6V systems went out of favor in the late 50s?
Small practical suggestion: Once the voltage is increased to 12V DC, there will be twice as high creepage currents since E=RxI and I=E/R assuming that the creepage resistance stays constant. Therefore, this will need to keep creepage surfaces clean and dry in many electrical equipment spots exposed to the hostile environment. Essentially, more frequent and more carefull maintenance/cleaning should be implemented.
