Looking a bit more into the Developer Connections CDs, I sadly don't think it leads anywhere. I found a pretty large archive of the discs from 1989 through 2009, looked through the following 2003 discs and none contain Mac OS X install images:Do you think I should try contacting Apple for it? Someone tried it a while ago and after being bounced around they were persistent and told to call them. They never did though as they had forgotten about it by the time they responded.
Edit: Found this on BetaArchive. https://www.betaarchive.com/forum/viewtopic.php?t=35149
Listed is "Dev CD Aug 2003 — Ghast has this". Does anyone have a beta archive account or know this person? They may have the build if they're referring to the Developer Connections CD.
It seems that prior to 2003, ADC made "System Software Edition" and "Seed CD" series' of the CDs which did contain the install images but then switched to only the "Developer CD" and "Developer DVD" series from 2003 onwards which just contain dev kits, documentation, training material, etc. I think the only build of Panther that was distributed on physical media was 7A179 (Developer Preview) at WWDC and then all others were distributed online for ADC members.