I have a Craftsman lawn tractor with 17 HP OHV model # 311707-0132-E3. It stopped running & now when I try to start it, it won't. It will crank a couple of times, but then won't even do that. On closer inspection a see gas dripping out of the front especially when I tried to start it. It looks like it is coming from an exhaust pipe, but I'm not sure what the 'box-like' part is in the very front (low) part of the engine. Thoughts? Thanks!

Check your oil sounds like you have gas in it.
Could be something in the carb holding the needle valve open.

You may have a flooded engine. Definitely check the carb float to insure it shuts off the gas flow when the float is raised. Also check to be sure you are getting spark. Remove the plug and plug wire, reattach the plug wire and ground the plug to the block of the engine, turn the key. Are you getting spark, if so what color is it

check your oil sounds like you have gas in it.
could be something in the carb holding the needle valve open.

DING... DING... you win (I loose) gas in the oil. Blown head gasket?

Gas in the oil can also be a stuck float that never quite shuts off the gas to the carb like DG suggested. Check the float operation with the bowl removed,when youraise the float does the gas stop? If so then we need to look further. Water in the oil of a water cooled engine might mean blown head gasket but we are thinking something else.