Thank you again.
1) I removed my current gupdate.gcd (version 7.50) from my nuvi 205 and added this downloaded nuvi2x5_regionfileonly__510.gcd later I renamed it to gupdate.gcd on my nuvi.
2) Created backup of folder GPX.
3) Turned off my nuvi 205.
4) When I turned it on it did not displayed the message New Software found or that the software is older.
5) I checked the software version in my nuvi 205 and it still displays 7.50 instead of 5.10
Shall I do something else or change some of the steps I did? I'm wondering if the HWID 1074 of my nuvi 205 is not compatible with the GCD file that I downloaded