Transfer Case Socket Size?

I have an 87 Jeep Cherokee Laredo 4WD, 6 Cylinder, 4.0 Engine, Automatic. I need a large socket for the transfer case fill/drain plugs. But I don't know what size it should be. HELP. Tried a wrench, didn't work.

1-3/16

Actually found a socket. It was 1 1/4. but thanks for the quick response. I also have an issue with the speedometer not reading. Yes I cleaned the part that goes to the transfer case. Also when Idle it shuts off and the key gets stuck in the ignition. Buttloads of probs huh?