That all depends on your mechanical ability and ability to follow directions. Just replacing the gasket is not that hard to do, but there are other things that you must be aware of. You must pull the engine, which means removing the PTO clutch and or stack pulley. This is not always easy. To lifting a seventy five pound in and out can be hard for some. Being able to live with mistakes that may occur, like getting in over your head, which will cost $$$$$.
I got the gasket on and all back to get her I replaced the oil seal on the shaft also but after running it for a while that seal is leaking not sure if I didn't get it in right or some thing