I bought a used Murray riding mower, 14.5 hp 42" deck, but can not find a model number on it. And now I need a deck drive belt. Under the seat I found someone had written the number 268-120-97. Can anyone help me figure out which belt I need? (I bought one at wally world, that was for a Murray 42", but it was too short) so I am guessing the mower is an older one. please help......