Ok I need some help. I just baught a 2004 Durango SLT. It has AWD and a 4lock option. The other version had a AWD 4HI and 4LOW. What I need to figure out is what is 4lock and when do I use or not use it? Any good for mud? Thanks for help. I also have traction control and don't see when I would use this seing how it is a AWD?