For mod gcd--> wiil not work because you use the same swv2.50
so ., chang swv to higher or lower.

For rgn ., it will flash to your nuvi.

for .gcd ., it's better to put in cs card\garmin

if your mod gcd is the same bytes --> it's right.

For me ., I like to use .gcd file.
DOn't worry., You use original boot.bin
Your nuvi will be ok.