Firmware file version 500 for Nuvi 255W?


Found a working Nuvi 255W at a thrift store recently. From examination of GarminDevice.xml it is running SoftwareVersion 500 (the PartNumber is 006-B0827-00, interestingly this is the same as my 265W). I want to try updating it to version 780 but need a copy of version 500 in case I have to put it back for any reason.

The Perry archive has files such as nuvi2x5W_GCDFile__780.gcd but there doesn't seem to be anything for version 500, and a google search didn't locate one. Does anyone have a copy of it or know where I can download it? Thank you.