Jiu-Kang Yu (1995) classified the isogeny classes of Drinfeld modules over finite fields in terms of Weil numbers and precisely described the isomorphism classes in an isogeny class of rank 2 $\mathbb{F}_q[T]$-modules. We further the studyby explicitly exhibiting/computing the Weil polynomials and precisely describing the isomorphism classes in an isogeny class for higher ranks $(\geq 3)$ Drinfeld modules. We also provide some results on the orders (of the endomorphism algebra corresponding to an isogeny class) occurring as endomorphism ring of a Drinfeld module.
Links:
[1] http://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/node/246