I can't help with the 6.4 but I had a '21, 2500, Cummins SO/6spd Tradesman 10k GVW, with coil springs and add on air bags. It was a quality truck with 50k miles on it when I traded it.
I now have a '25, 2500, Cummins HO/8spd Bighorn 11040 GVW, with coil springs and add on air bags. Only 11k miles on it but seems to be another quality truck.
I really like the interior/exterior of the 4th gen Rams. The 2500 rides and drives great. With the sway bars front and rear and track bars front and rear, it corners like it is on a rail, loaded or empty. If you have any specific questions I will try and answer them.
Look closely, because they are almost identical, first picture is the '21, 2nd is the '25.
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