What kind of grease gun tip to I need to grease the flat zirk fitting on the Dynatrac ball joints?

A needle tip. You can find one at any part store.

Thanks. After I posted, I found an unopened needle tip in the bottom of my toolbox.

We recommend greasing them once a year if you live in a state where road salt and snow are an issue. In other areas, do it when you do your scheduled diff oil changes.

Once a year makes it easy. Thanks again.