  We discuss the steady state dynamics of interfaces with periodic boundary
conditions arising from body-centered solid-on-solid growth models in $1+1$
dimensions involving random aggregation of extended particles (dimers,
trimers,\,$\cdots,k$-mers). Roughening exponents as well as width and maximal
height distributions can be evaluated directly in stationary regimes by mapping
the dynamics onto an asymmetric simple exclusion process with $k$-\,type of
vacancies. Although for $k \ge 2$ the dynamics is partitioned into an
exponentially large number of sectors of motion, the results obtained in some
generic cases strongly suggest a universal scaling behavior closely following
that of monomer interfaces.
