The ONLY reason that the EB is standard is because it is there to provided a load to the engine during active regens.
Say WHAT??!?!?!
That could be the craziest reason I have ever heard of for an exhaust brake. There is no load needed for an active regen to occur as it's a chemical reaction in the exhaust.
The exhaust brake is there to provide braking while decelerating and descending, period. It's saves the the service brakes and controls speed.
If the exhaust brake were to apply with fuel being injected BAD things could happen. EGT's would skyrocket, back pressure would be thru the roof, and who knows what other funky things would go on. This could be very bad under heavy power and light power.
All 6.7's, in pickups, came with the exhaust brake feature (It's a function of the turbo and not an actual exhaust brake like the 5.9's and other engines use). The C&C's had it as an option at first but it soon became standard. Even those without it just needed a software update.
All 6.7's have DPF's OEM, 3rd or 4th gen. There was never a non-DPF 6.7 put into the Dodge/Ram.
The 5.9 had a DIO (Dealer Instsalled Option) for an exhaust brake on the later 5.9's. I am not sure what year it became a DIO for the manual transmission (late 2nd gen comes to mind) but it was first offered for the auto's for MY06.
The Nissan Titan with the ISV 5.0 Cummins does regens like all other motors and it has NOTHING to do with the exhaust brake. Fuel is injected (either with an additional exhaust injector or the main injectors) that goes unbrunt into the DPF. This then increases the temp in the DPF to the point where it cooks the soot out of the DPF. Many diesel engines have DPF's and do regen's without an exhaust brake. There are plenty of pdf's and youtube video's on how active and passive regen work if you want a more detailed answer, this one was very general.