hi i just purchased a john Deere 410 tlb with no backhoe, year is unknown but should be about the early 80s and i am having issues starting it it has the 4 cylinder diesel and and when i crank it 3 times it kills the battery so have to jump it then starts my question is does it need 2 batteries or just one and what size battery does it need cause right now it has 1 875 cc exide marine/RV battery in it and i tested it and took it to get tested at the auto parts store and they said it was good battery and they charged it for me but still having same issue thanks