Interesting topic ?.
Unfortunately, you're the Unicorn in the room, with so few of the ZF6 combos made, even more so with your '2' LLZ. Not because it's flawed, there's just not that much info out there from Users.
The mod for waking up the Turbo Brake is based on Medium Duty logic left in the ECM used on the Light Duty. I don't think the Kodiak/Topkick ever came with a manual trans, so wondering too if it (TB) was ever in the ECM tuning, which would be somewhat different for the manual trans.
In using the TB with the Allison, 1st comes the grade braking from the TCM, and then a few seconds later, the TB kicks in on top of that. Increase the throttle just a tad and the TB drops out, then let off and it kicks back in.
It's not instantaneous like with a Jacob's Brake or a true exhaust brake with a butterfly valve just past the down pipe. More subtle.
It'd be interesting to know if it works on yours.
Try the mod and see?
I've often thought about how the feel is like with the ZF6, running grades and towing, vs the Allison.
Raised on a Manual, I had considered an Auto as a disposable trans for those who didn't have the coordination for clutch shifting, as I had so many fail over the years.
I had sworn them off, never again.
So I was very apprehensive going into my 1st Dmax/Allison from my old 6.5T 5-speed shaker, when they 1st came out.
That's now a thought in the very distant past, as I no longer walk with a limp,....my left leg as returned to the same size as the Right.
2007 LBZ 3500 LT3 DRW Crew Cab, Sulastics, Putnam XDR 15K, B&W 30K-Turnover GN+Companion, Ride-Rite Air...EFI'd by Rob
2008 LMM 3500WT DRW Crew Cab, 8 'Flat/GN, Workforce Alum Toolbox, Ride-Rite Air Use-ta Haves 2006-6.0 3500 WT DRW ExCab Flatbed, 2005-LLY 3500 LS DRW Crew Cab, 2002-LB7 3500 LS DRW Crew Cab I Live my life in such a way that when my feet hit the floor in the morning...Satan shudders & says "Oh shit, he's awake!"