I have a custom field type with a fldtypes_xxx.xsl template that we have carried forward from a 2010 solution into a 2013 solution. The Number_body template we are using works just fine. However, I cannot get the header template to work.
For the FieldRef I have tried matching the ID, FieldType, Type, Name, StaticName, etc. Nothing seems to be able to get it to use the header template.