For the 2015 Ram, the axle ratios are stated below
On the Ram 1500 lineup, there are three available axle ratios – 3.21, 3.55 and 3.92.
The base axle ratio on 4×2 gas trucks is 3.21,
4×4 gas trucks is 3.55
the biggest axle ratio on 4×4 or 4×2 gas trucks is 3.92.
The base axle ratio on 4×4 or 4×2 diesel trucks is 3.55
the biggest axle ratio on 4×4 or 4×2 diesel trucks is 3.92.
As shown in the previous section, larger axle ratios can substantially increase towing capacity.
The max towing capacity of a Ram 1500 with a 3.6L Pentastar engine goes from 4,850 pounds with a 3.21 axle ratio to 7,100 pounds with a 3.55 axle ratio — which is almost a 50 percent increase. The percentage increase is not quite as significant with the 5.7L HEMI engine. With the 5.7L HEMI the 3.55 axle ratio provides a 25 percent increase in towing capacity in comparison to the 3.21 axle ratio.
I tried finding the specs in Rams official site, but my computer is not set up to read it