First, be sure you have heavy enough battery cables on your tractor. Remember, 6 volt was marginal even when these tractors were new. You might want to try an 8 volt battery which is completely compatible with your 6 volt system. It does make a big difference. I have them in a 1949 88 std. as well as a 1950 mercury truck.  Simply install as if it were a 6 volt ( positive ground)     Good luck, Murray