This shows AC3D 1.58:
http://www.tin.it/sbdi/50/graf50it.htm
The view windows used to be seperate but you can see that the overall interface is still very similar.
AC3D was initially developed on an Amiga (with an X style widget library), then it moved to an SGI and a 486 PC running Slackware Linux.
The earlier versions used X-window Motif (rather than TCL/TK) for the interface, I'm not sure if there any images of that - this was really just at the time the WWW was starting. OpenGL was quite new then too. The rendering was written in pure X and SGI GL.
The version history
http://www.ac3d.org/ac3d/versionhistory.html is interesting reading for me, but it's not beautifully formatted.
Andy