Not too many places that the trany could leak from. Coolent leak could be freeze plugs but I've seen the pump to intake hose leak and run down the block and under. Hard to see. Some auto parts stores loan testing tools. Get a radiator pressure tester, fill it with coolent, and put the system under pressure. That will help find the leak.
If it is the freeze plugs pull the old ones before you drive the new ones in otherwise you just add contamination to your cooling system Then they end up looking like this that I pulled out of an engine I bought in Washington.
