PostgresSQL 7.3.x removal

Attempting a FreeBSD install of 7.4.3, apparently remnants of 7.3.x are
scattered around on the disk from (a) previous ports installation,
causing mutex_lock/unlock, libpq.so and other installation problems. How
do I know what, & where all these fragments are located or how do I
uninstall all of them or at least those that should be removed.

Thanks

-- Adam --