If you look at the instructions it does show the 2008 6.4Yeah, BD misnamed it. It's not a "timer", it's a controller just like the TTM. And it's very hard to find on the BD website. But I found it, so here it is:
BD Power - Product: Cool Down Timer
Their website doesn't mention the 2008-up 6.4L engine, but call them and I'll bet they say it will work on your 6.4L too.