My new trim sender wires have a male and female round connector on black wires instead of the black w/purple sleeve on one of the wires. Which connector is the negative? the male or the female?

Formula31... the sender is a variable resistor so I don't think it matters which direction the current flows through. Should get the same result either way.

BT

I hear ya but one is the wiper and the current flow might matter for life. Since Merc has them polarized I would like to keep it the right way. Darn things are expensive and dont work for long the way they are.

Polarity in a non motorized, non switching DC application is generally not a problem if reversed. I can't see why it would matter and I suspect that is why both conductors going to the sender are the same color.
Albeit, I understand your desire to do it right. If you are still in search of the answer next weekend I'll take a look on my boat when I go down.

BT

Blue thunder on the money James