Try Amazon this site usually has everything you will need for an RV. Also check with your dealer to see if they have any in stock. This switch is just a simple rocker switch that returns to neutral when release. You might also find a similar switch at an on line RV salvage yard. Also E-trailer might have what you need. Do a Google search.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67, TDR 135K+miles