the radios in the 4th generation Rams are all 1.5 DIN i believe
with a little modification, a 2 DIN radio will fit, several members have done it
Most aftermarket radios are single DIN which have face dimensions of 50mm (2 inches) tall by 180mm (7 inches) wide. A double DIN is twice as tall and the same width. The radios do vary in depth and it is very important that you know if the radio you want will fit in your dash.
Usable space behind your dash for a new stereo: 10.474"
you may want to read this website, it may help a bit, pay attention to which radios use the high bus speed
that is what the Gen 4 Rams use