The gear ratio was a concern of mine when I was looking into getting a different truck. There's a pretty big difference between the 4:10 ratio and the 3:73 ratio on the RAM I just bought. With 4:10's my tow rating would've been something like 28k or 29 k.
I wanted the 3:73's basically for a little better fuel mileage. MY tow rating is just UNDER 24k, which I'm comfortable with. For some like 12V98, he wants the heavier towing capacity, it's just personal choice.
If you go with the 3:42 ratio on the RAM the towing capacity drops below 17k, so ratios due impact tow ratings significantly.
Dan