Did a little digging today to figure out how to open a very old Illustrator file with CS6, here's how it works: Open the old file (that just won't open in Illy for you) in a text editor. In your newer version of Illustrator, open a blank page and save it backwards to Illustrator 8 (All of the CS versions up to CS6 will allow that, I don't know about CC). I named mine Old Illy Converter so I could find it later. Now open that in the text editor. Copy the header down to, but not including the bounding box info line, in my example it's the first 7 lines. Now paste that into the old file that's opened in the text editor to replace those same lines, right up to the bounding box line. Save the file, and add a .ai extension to the name. Open it in CS6 (or CS - CS5 I would imagine). It's working for me, so I thought I'd share it with everyone that have given me so much help over the last few years...
Steve
by the way, it works with a .txt extension as well.
