This is exactly the info I've been looking for, Moses. Many thanks!
Weight, length, ratios, parts availability and price, adapters available, all these things I could find out online, but this one question has eluded me for weeks, until now. With nothing to chose between the two for noise, my decision can focus on other factors. Both these boxes are relatively bullet-proof, both will fit within the length restrictions, and both are generally available at reasonable prices in my area. The decision may come down simply to which one I can find in the best condition for the best price at the time.
The background here, is that I'm planning out my new project, a replacement for my current vehicle. This to be my sole daily driver, not a weekend hobby. Our climate, my location, and my work responsibilities make a 4WD pretty much a necessity, but year-round it will do many hours of pavement driving, so I needed to consider noise, if there was a clear-cut difference. You've removed that concern for me. Thank you again!