% mod2.sty
\renewcommand{\@makechapterhead}[1]
{\vspace*{3em}
 \centerline{\uppercase{\thechapter\quad #1}}
 \vskip1em}

\renewcommand{\@makeschapterhead}[1]
{\vspace*{3em}
 \centerline{\uppercase{#1}}
 \vskip1em}