THanks for the quick response - I think i tried that early on just out of habit (always try something with -devel ending) but it did not find anything so I figured there was no such thing. But sounds like I just have to figure out what repo I'm missing.
[root@rcadmin:~]# yum --enablerepo=* -y install rrdtool-devel centosplus 100% |=========================| 1.9 kB 00:00 primary.sqlite.bz2 100% |=========================| 203 kB 00:01 Setting up Install Process Parsing package install arguments No package rrdtool-devel available. Nothing to do [root@rcadmin:~]#