I have a Craftsman lawn tractor Model 917257642 Serial number 0420948 001807. It has a 15 hp engine. I need to know to help find a replacement engine.

Hi,
Too old a machine to get a manual. Sears does not divulge the engine specs. You will need to furnish the numbers off the engine for me to help.
Double check your model number to make sure that it is correct, as there is a model with the digits transposed.
Peace,
Clarke