1997 suburban transmission/transfer case leaking

While towing a trailer that weighs maybe 2500 pounds, I noticed that my suburban didn't like to shift. I noticed that I lost almost all my transmission fliud. It is not wet around the transmission itself it is soaked all over the transfer case. I noticed a hose that looks like it could be a vent hose that is on top of the transmission could this leak? Also is it possible for the transfer case oil to mix with the transmission fluid. I think when I pull the dip stick out that it looks like there is gear oil on the stick. Is this possible? Please help, transmission still shifts fine I am just not going to drive it until I find out how it leaks.