Need help on my Silverado.. Grinding.. Whirring sound up front in 4WD

Well sad update today.
Been up under the truck.. nothing leaking.. nothing visible. I had to run out into the jobsite today to get a floor scraper, came back and noticed when I was loading up my tools something on the ground.. some type of fluid. She has started to leak- past the CV joint- at the differential. So the seal has finally worn out. The grinding whirring may be a bearing on the pinion bearing or hogs head.. So for all the labor and time to tear a differential apart and rebuild it- I'm looking to get a used one tomorrow- whole differential.. ****!