  Because of the top quark's very large mass, about 175~GeV, it now provides
the best window into flavor physics. Thus, pair--production of top quarks at
the Tevatron Collider is the most incisive probe of this physics until the
Large Hadron Collider turns on in the next century. In this talk I discuss how
moments of the $\ttb$ invariant mass distribution can be used to distinguish
among standard and alternative mechanisms of $\ttb$ production.
