VW Electrics Wiring heated LT Mirrors
Wiring up heated syncro/LT mirrors
Syncro mirror arms were originally non-heated whereas some LT arms were sold with heated mirrors with the wiring fed through the arms.
However heated LT mirrors can be bought from VW cheaper than standard mirrors (281-857-547C) and they are the same sealed unit as Syncro mirrors but have wires attached. (Note: this is just the reflective unit the arms are different between LT and Syncro but can be made to fit.)