No sure haven't, but the balance shaft is in no way shape or form connected to the transmission or transfercase anyhow, so the engine isn't going react different during 2wd vs 4lo when around 2,000-3,000 RPM range.
Well, except for the fact that they
ARE bolted to one another....
The myth of vibration would technically occur all the time the car was running in the 2,000-3,000 RPM range regardless of gear selection, however in the case I have witnessed no irregular vibration occurs at all.
Not true. Harmonic vibrations can occur under a whole host of operating conditions, not just a specific RPM.
Well first off, the "myth" about the balance shaft is that when a 2wd SOHC(no balance shaft) is placed in a 4wd SOHCs place that had a balance shaft, a vibration in a certain RPM range will be noticeable(or possibly other damaging side effects). I took on this project and busted the myth. Many members want to know if the swap could be done, and have been told that adverse effects or complications such as our "vibration" can occur, by members with no experience(not knowledge, experience). I know and have heard of many members who have seen great deals on donor engines but were 2wd SOHCs when they supposedly needed a SOHC with a BALANCE SHAFT or else!!!!!!!!! I am just giving those members who are skeptical or nervous some proof. As for "I don't think one instance of no vibration means that others may not have this occur".....Facts are instances that have been proven and leave no room for error, and I am proof. This myth remains debunked
The engineers that developed the engine spent tens of thousands of hours doing NVH testing under a whole lot more widely varied operating conditions than your 2000-3000 RPM test, and determined that the balance shaft was necessary for some specific reason. It's likely that the extra weight/inertia/shape/polar moment of the transfer case added to the driveline, or possibly the front half of the driveline adversely affects the vibration of the engine, or the engine itself transmits vibrations in some undesirable way to some component (be it the engine itself, the mounts, the passenger compartment, or any of a thousand places) and tha undesirable vibration is unique to the 4x4 drivetrain in some way. At any rate, it was installed there for a reason, so unless you know something the engineers don't, I don't think you can call it a 'myth' in the first place, let alone 'debunk' it based on one instance.
The question was never whether or not it was possible to bolt a 2wd engine into a 4x4 truck. They are the same engine, aside from the balance shaft. The question is whether or not doing so would have any negative side effects. One can only infer from the original design that there was some specific reason the engineers opted to install the balance shaft on ONLY the 4x4 vehicles, and one can logically infer that the engineers would not have insisted on installing it if there wasn't a need for it. Should you choose to do otherwise, then it must mean you are much wiser than all the engineers that designed, tested, and developed that engine.... And that's a pretty bold claim, IMHO. I guess nearly 20 years of powertrain development must be wrong....
Let's not overlook the fact that it would appear that now ALL of the SOHC motors include the balance shaft, regardless of whether it's a 2wd or a 4x4. I didn't check to see exactly when that change occurred, but the service manuals for the '09 no longer specify the balance shaft for 4x4s only.... Again, if there was no benefit derived from it, they would have gone the other way and removed it from all the engines.