Look for your garmindevice.xml in your nuvi.
In the first lines you can get your device HWID
<?xml version="1.0" encoding="UTF-8"?>
-<Device xmlns:dtlx="http://www.garmin.com/xmlschemas/GarminDeviceExtensions/DataTypeLocation/v1" xsi:schemaLocation="http://www.garmin.com/xmlschemas/GarminDevice/v2 http://www.garmin.com/xmlschemas/GarminDevicev2.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.garmin.com/xmlschemas/GarminDevice/v2">
-<Model>
<PartNumber>006-B1376-00</PartNumber>
In this case 1376 is the HWID of my nuvi -
Different nuvi 2x5 chipsets get different firmware, so you must use the right one or you brick your device.
MTK version is 1074, other one is 851.
You can flash it using the sd, remove any gupdate.gcd in nuvi, put the new gupdate.gcd in a Garmin folder and insert the sd in nuvi. It will flash the firmware.
Regarding regions:
Quote Originally Posted by dasilvarsa View Post
Regions are flash memory blocks in the Nuvi (These vary in size)
e.g. Region DEC 16 is the logo.bin region. Region Hex 0C is boot.bin - Region hex 7F is Fw1_resources.bin Region Hex 0E is Fw_all.bin
Some Regions contain critical information eg Region DEC 139 contains the part number and Revision on Nuvi 37xx/34xx
Region Dec 41 is the NVRAM and is unique to a particular Nuvi
Regions can be different in old Nuvis like 2xx or 3xx/6xx. Probably region 41 doesn't exist in these old devices, but I'm not sure.
This thread is old, links are dead (removed now) if you need a file ask please and I'll reupload.