Thanks to Ron for diode info.

Replaced the IPD diode I blew up, installed and everything lit like it should. And relocated the ballast resistor. (that still ticks me off)

So with the correct wiring the swap really isn't a big deal, I think my experience was kind of a fluke 'cause there just ain't that much to it.

Seems the one thing that does make a difference is whether you have the coil from the '75 or you are using the original. I don't know if there is a difference in output with the '75 coil.

I bought my setup already pulled and without coil, so the diode seems to be a big deal. Because I couldn't get anything without that thing controlling current flow.

Wish I could explain why this is critical, but electricity is simply an on/off concept to me; beyond that my head starts to hurt.

Anyhow, its running and timing is stable. On to other things.

Thanks to all who offered input, always a help in understanding how its supposed to work and then figuring out why it isn't.

-Mario E.
Lawrence, KS