Starting with a brief description of dyons and gravito-dyons, combined
field equations and the equation of motion for generalized electromag
netic and generalized gravito-Heavisidian fields are derived in a mani
festly covariant way. A non-Abelian gauge theory of dyons and gravito-
dyons is described in terms of a generalized Yang-Mills potential, fie
ld strengths, and generalized field equations each carrying electric a
nd magnetic constituents. A null tetrad formulation of a generalized Y
ang-Mills potential and field strength of dyons is discussed in detail
in terms of symmetric spinors and spin coefficients. Generalized Yang
-Mills field equations of dyons are rewritten in terms of null tetrad
notation, and dyon solutions of source-free Dirac equations are obtain
ed.