Fits John Deere tractors like the M, 40, 70, 320-430 that use the Delco Distributors with the clip held cap through 1963  tractors. This shiny cap not only looks as good as the new original cap, it also performs better because this cap doesn't "Chalk" like the original.  It will hold the shiny new look for many many years.  Replaces John Deere Parts 1909008.

Why is the Cap Voltage Important?
The index built into the cap only allows Distributor Cap installation in one position. The 6 Volt cap is built so that it is timed 90 Degrees out of engine timing from the 12 Volt cap. Therefore, if you have the wrong Cap installed in your system your engine won't start or run.  If someone has tried to convert the electrical system on your tractor from 6 Volt to 12 Volt this may further complicate the question.  In this case you still need the 6 volt cap - a voltage change of the battery doesn’t mean you have changed the timing of the distributor. See the new tutorial at Meli's Tractor school for an in depth study of this question