There are two plugs. One is a filler hole and the other is a check valve. Maybe someone on here can post a pic or an image (I don't have any sorry). Open the check valve on the transfer case, fluid should dribble out. If it does, you are good. Close it up before you loose too much. The differential is kinda difficult if you are on level ground and can get to the filler hole you should be able to stick a finger in there and feel fluid right at the hole. The reason is when you fill the transfer case, you open the check valve and filler hole. Keep filling it until fluid comes out the check valve. On the differential, you fillit untill fluid starts to come out. Keep in mind botch should just dribble, not be filled to the point that fluid is gushing out. Also, I am not sure about your area, but there is a toyota dealer here that will change the differential and transfer case fluids for a very reasonable price. Like around $85.00 for all 3. It is easy to do your self too.