Welcom Robert, You are with the best forum on thw web IMHO.

SOunds like the heater core to me. Yuo will have no antifreeze in the cab, it drains at the rear of the Passenger wheel well. Open your glove box and push in the sides to allow it to swing completely down. You will see a 8x8 inch plate with serews around it. Take it off, there is the heater core. You will notine the lovely puddle of coolant at the bottom.
It is easier than it looks to replace. Have fun with the disconnects!

Doug