This may have already been answered... Does anyone know if the main and aux tank sending units are the same? One of my mains is getting sketchy and I have two aux senders I'm not using at the moment! Thanks!

Think so

I have a full set of brand new EI P-300M for M4/'5 tanks I'd sell for $300ea. if anyone has an Electronics International engine monitor to use them with. They've been installed in the tanks, but removed before ever seeing fuel.