[bsmith0404]

With the power these new diesels are putting out, there really isn't an RV that is going to cause them problems on pretty much any road we can take them down. The main consideration is the max torque point. That is where your most capable power is delivered as well as where your best fuel mileage is achieved. So the combination of transmission final gear and rear end gear has to achieve that at an acceptable highway speed. The GM 3:73 gear puts the Dmax at that point right around 65 mph. Which is also considered a safe towing speed by many people, coincidence? Using the 6 spd Allison gearing, they can achieve plenty of take off power to get you rolling out of a hole. It's the combination of the two that creates a useable package. Don't put too much thought into what the rear gear ratio is these days. It's not as significant as it was in the old days with gas engines and 3 or 4 spd transmissions.