Module, Electronic Ignition (W/ Prestolite Distr. # IBT4101). PART NO: A-21A305. For 4 cyl. models w/ 12 volt negative ground or 6 volt systems converted to 12 volt negative ground systems only. . MODELS: John Deere TRACTOR: 2510 (W/ Prestolite Distr. # IBT4101) John Deere TRACTOR: 2520 (W/ Prestolite Distr. # IBT4101).