Can't find SRPMs for PG 8.1.18 on RHEL4

I'm having trouble finding the source RPMs for PostgreSQL 8.1.18 on
RHEL4. I've tried looking in the following places with no luck (I can
only find the regular RPMs).

http://yum.pgsqlrpms.org/8.1/redhat/rhel-4-i386/
http://www.postgresql.org/ftp/binary/v8.1.18/linux/srpms/redhat/rhel-4-i386/

Any suggestions?

--
Justin Pasher