GM transmissions all have unique pan configurations so you can identify that component rather easily. The engine will have a number on the upper left flange of the bell housing that will ID the engine in a general sense. The right front side (passenger) of the engine block just behind the altenator will have a small rectangular land area on which should be stamped a series of characters/numbers. If the block has not been decked in the past these should still be there but may be under a layer of crud. If you find those characters there are several sites that define what these engine codes/suffices designate.