I believe all of the new HDs with a diesel have an engine brake. I don't know about the Ecodiesel. Some of the 'older' diesels with a VGT turbo can have an engine brake feature written into the ECM program. I have one on my 6.0 and it works surprisingly well; no hardware required.

Mercy ceases to be a virtue when it enables further injustice. -Brent Weeks

~Molɔ̀ːn Labé Skýla~