Your DO NOT need to rebuild anything.
You DO NOT need to force anything.
If you try either of these, even if you get the install to work, serviceguard will not work. Admittedly, the error message is a little cryptic. I beleive that part of that is due to how RPM works and may be in part to the fact that you have a force option.
I assume you are doing this with RH3 since that is the RPM you are using.
Either way, you need to uninstall authd and install the version of pidentd that comes with Serviceguard. This part is very well documented in the release notes. These are on the CD.
I'll be monitoring this thread carefully now.