I got my rear pinon seal fixed, and while I was under there I noticed I have a decent amount of oil on the tranny pan, and transfer case. apparently I dont crawl under my truck enough! could it just be the gasket on the tranny pan? or am I looking at something worse?

 

Start with steam cleaning the everything , then short trips [ short because you want to see where the oil comes from ] , then fix the leak when / where you find it .
Another way , but need equipment , is a dye in , what ever is leaking , engine oil , trans. ect.
Then use a black light to see where the dye is coming out , again check early & often , so you can see where its coming from .