Need ideas - trans fluid loss
Due to unfortunate radiator failure had to remove tranny. In a hurry, had a used one from bone yard installed and drove it home from shop. Was a little slow engaging but shifted OK. Checked fluid and found it 1/2 qt low - topped it of and seemed fine. After sitting in driveway for a couple of weeks noticed large puddle underneath. Checked fluid and not even registering on dipstick. Now it will not move although it does engage in F & R. What should I check first?