Looking for older Cisco PIX-520 images

I have this recently acquired PIX-520 with what seems to be an entirely *blank* FLASH boot card. The machine is so clean inside - not a speck of dust - that I think it may be a NIB unit that someone decided to disgorge onto eBay last summer. It goes through the usual PC-ish boot dialogs (there's an Intel Pentium board inside, with 3 Intel NICs and a 3.5" floppy as the only peripherals besides the boot board), but when all the PC stuff is done, the unit acts dead - no traffic on the serial port that I can see, no text on the (installed by me for debugging) video. I'd try the Cisco site, but besides lacking a current log-in, from reading some of the firewall mailing list entries about older PIX OS files, it seems that Cisco may have purged some of what I'm looking for. If anyone happens to have any archived files from older versions (pre 6.x) of PIX OS and the attendant boot helper files (secondary bootstraps), please contact me *off list* if you are willing to share. For starters, I'd love to find a file like bh510.bin, bh512.bh or bh514.bin, which are various versions of the "boot helper" for the less-obsolete versions of the OS. If I had a boot helper file written to floppy, I should be able to at least see some activity related to it _trying_ to install the OS. Thanks, -ethan