I am leaking ATF fluid underneath my truck and along the driver's side. Hard to tell if the leak is coming from the transmission to the differential. It's only leaking a couple of quarts. First noticed it when I pulled a light load (approx. 5k lbs) down the highway at 80 mph. When I stopped, I had to add approximately 1.5 quarts. Any suggestions, as to where I should start troubleshooting? When I come to a stop and let off the brake to roll a head an extra foot, the transmission shifts hard. Any and all help would be appreciated.

Sounds like it's coming from the overflow.

where is the overflow?

Directly on top of the case towards the rear. It has a metal cap on it.

I'll look at it tonight, when I get my truck back and let you know. Thanks

Found out my problem this morning. The transfer case just behind the tranny is cracked.