Please look at these drbd83 and drbd-kmod83 testing RPMS:

http://bugs.centos.org/view.php?id=6341

The link to the actual RPMS are there, here it is as well:

http://people.centos.org/hughesjr/drbd/5/

Please provide feedback to bug 6341 (first link above) and we can get these moved into the extras repo.

Thanks, Johnny Hughes