tcl-devel build dependencies for 7.4.2

I am trying to build Postgres 7.4.2 from the source rpm on Red Hat Linux 7.1
2.96-98

I get the following error message:
[root@CISX_Linux1 usr]# rpmbuild --rebuild postgresql-7.4.2-1PGDG.src.rpm
Installing postgresql-7.4.2-1PGDG.src.rpm
error: failed build dependencies:
        tcl-devel is needed by postgresql-7.4.2-1PGDG

My problem is that I can't find a binary or a source for tcl-devel for Red Hat
Linux 7.1.
My current version of tcltk is 8.3.3.
I tried the Fedora core 1 source from Red Hat (tcltk-8.3.5-93.src.rpm) but that
fails miserably....

Does anyone know how to get around this problem or alternatively are there any
Red Hat 7.1 binaries for PostgreSQL 7.4.2?

Thanks in advance
Donald Fraser