Hi Randy, Ok I put the Chimera 1.2318 Mac OSX PPC headers on the web that correspond to the corresponding snapshot on our download page. These headers were used for compiling on a G5 Mac OS 10.4.8. Only two headers files are different for the different operating systems: pyconfig.h and tiffconf.h. Here are the headers: https://www.cgl.ucsf.edu/cgi-bin/chimera-get.py?file=source/chimera-1.2318-o... It may take an hour for the web page source code table http://www.cgl.ucsf.edu/chimera/sourcecode.html to be updated. Tom