This is a 12-Volt Delco 40MT Starter, Using DE Housing #1969323 (Others - All Have 1/2" Mounting Holes), a 12-Tooth Drive (Accurate #4-489), and Lester Armature #1866. The 6238 is the Same Unit, But With an Overcrank Protection Thermostat. The 3999 is the Same as the 3374, Except the Solenoid Terminals Are Reversed. The 6237 is a 3999 With an Overcrank Protection Thermostat. The 3370, 3955, and 4987 Are All 24 Volt Units That Use the Same DE Housing and Drive. The 3339 is the Same Unit in Appearance, But Has 5/8" Mounting Holes. John Deere is Selling Their TY6697 to Replace the Other OEM Numbers Listed Here.