Yes, 8.351 is your navcore version. You can leave that as is, no need to update it. I suggest you download the latest and the new v860.3101 North America map if you can.
Here is all you need to do:
- Using windows explorer, open your device directory and delete the old map folder(s)
- Create a new folder and rename it "North_America". Extract the new map and copy across the contents into this folder
- Copy paste fastactivate.exe into the root of the device directory
- Run fastactivate.exe making sure you run each of the 4 options in order
I should also add, for your particular model, if you prefer to use the SDHC card, then firstly using Windows Explorer copy the entire contents of your device directory into the SD card then proceed with the above steps. Note that whenever you have the SDHC card inserted into your device it will only read what is on the card. It won't even look at the internal memory.