I've seen one post where a 2015 SRW 3500 was able to be ordered with 3.73. This link seems to agree. What throws me off is a 6000lb front axle option. Makes me question the validity of the site. Click on the engineering tab under packages and options to find the gears. I hope it's correct and stays that way.
http://www.intellichoice.com/1-12-20...-packages.html
http://www.intellichoice.com/1-12-20...-packages.html