To download .srd you only need GarminDevice.xml with tags for srd. Version numbers should be decreased for WebUpdater to show update.
This is set of tags from patched 3760:
Maybe srd for 34xx have different part numbers, we need a qoute form its xml.Code:<UpdateFile>
<PartNumber>006-D0808-00</PartNumber>
<Version><Major>2</Major><Minor>10</Minor></Version>
<Path>.System/ASR</Path>
<FileName>English_American.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D0807-00</PartNumber>
<Version><Major>2</Major><Minor>10</Minor></Version>
<Path>.System/ASR</Path>
<FileName>English_British.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D0811-00</PartNumber>
<Version><Major>2</Major><Minor>10</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Deutsch_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D0813-00</PartNumber>
<Version><Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Nederlands_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D0810-00</PartNumber>
<Version><Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Italiano_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D0812-00</PartNumber>
<Version>
<Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Espanol_European.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D0809-00</PartNumber>
<Version>
<Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Francais_European.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-DXXXX-00</PartNumber>
<Version><Major>0</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Mandarin_Chinese_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D2414-00</PartNumber>
<Version><Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Pycckuu_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D2413-00</PartNumber>
<Version><Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Dansk_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D2412-00</PartNumber>
<Version><Major>2</Major><Minor>10</Minor></Version>
<Path>.System/ASR</Path>
<FileName>Svenska_.srd</FileName>
</UpdateFile>
<UpdateFile>
<PartNumber>006-D2415-00</PartNumber>
<Version><Major>2</Major><Minor>0</Minor></Version>
<Path>.System/ASR</Path>
<FileName>English_Australian.srd</FileName>
</UpdateFile>
Edit: firmware for 34xx uses value CE 0E? Then this is based on firmware for 3790? ;)