Have a 2006 2500 4 x 4 diesel that I bought new, great truck very few problems runs great and everything works as it should. Time to sell her, will miss this truck Someone is going to get a good truck. Now I have purchased 2020 3500 dually HO diesel only 100 miles love it so far. There are two switches down on the dash beside the exhaust brake with a symbol and it says park front on one and park rear on the other what are they, can't find any info in the manual. Thanks N wood