All you need is gupdate.gcd in .System folder! The nuvi55_56_450.gcd is the same gupdate.gcd for you if you have version of 4.50 of SW in your device. Do not have it - it is not problem. Goto here:
- GPS Navigation Systems Sections
- Garmin GPS System
- Garmin Receivers Firmwares
[Only registered and activated users can see links. ]
and download nuvi55_56_450.gcd from link in this post directly...