1997 Mitsubishi Galant Transmission not ingaging

97 Galant, 2.4 SOHC automatic tranny. I let me mom borrow my car that has never had a problem in 4 years and she gets 40 miles away and a freeze plug in the head pops out and it gets real hot, only she never watches the gauges and it over heats and crackes the head and started burning up part of the head between the exuast valves on 2 center cylinders. I pull the engine, replace the head, gaskets, water pump, timing belt, plugs, oil and antifreeze. It starts right up and we getting running smooth, let it off the jacks, put the hood on and it will not move. It wont roll when its in park, but putting it in gear does nothing. We checked the fluid, even drained it and refilled it, and it is full. We checked the gear selector on the transmission and its clicking threw all the gears. We split the engine and tranny again and checked the torque converter and it feels like it is in place all the way and it has no play in it and it turns real easy. The drive shafts are good and locked all the way into the tranny like they should be. All the plugs and clips are connected and hoses are in place ( we never pulled the tranny, we left it in and pulled the engine and the torque converter never came out )We ahve ran out of idea's and the tranny was working fine when the engine blew doing 75 mph down the inner state. Any help would be great, Thanks alot, Jim