That's the part number for a Massey-Ferguson 6 speed transmission case. Looks to have been used on several models. There should also be casting numbers on the axle housings, engine block, steering housing, possibly front axle, and anything else that is cast iron. Find all of the numbers you can, and write them down, then do an internet search (I get the best results using Google). That may narrow down what you have, if they used a specific housing/part on a certain model.