As I remember your device support TTS3 voices.
You can see a list all of it with this searching string in a browser:
Unfortunately Garmin removes the download links from HTML source now.Code:Please Login or Register to see the links
Only for English voice you can use my garmindevice.xml file:
[Only registered and activated users can see links. ]
Unpack it on a flash drive or a SD card into Garmin folder (create this folder). Run WebUpdater and download that you want only TTS3 or all with additional voices without TTS. After that copy the downloaded files into your device.
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