Add character to barcode field

I need to add a character to a field formatted as a barcode.  The character will help route the information to the correct users.

I've tried formatting the barcode using the !Format event field but I'm not getting good results.  I need to add an "E" to one barcode and a "3" to another

I've tried E@_$_. and other variations.  Anybody have suggestions?  These are global fields in the DAT file.

using output designer 5.5