On our 2003 it had the "silver can" type which is a mechanical flasher. It actually had two in that location, one for the turn signals and one for the 4-way flashers.
The 2004 is a electronic control module that controls all the light functions, tail lights, turn signals, four way flashers and running lights. It is quite expensive to purchase and can only be purchased thru Freightliner I was told. I believe it costs somewhere in the neighborhood of $160.00 if I remember correctly.
I believe Freightliner started using the Module in the summer of 2003.
The dealer had to replace two of them in the first year of ownership of 2004 coach, thank goodness they were covered by warranty. Since then we hadn't had any more problem.