I really can't follow what you are describing. Remove the legs from the dishwasher and it may slide in. If it is still too high then you will have to remove some of the wood over the front of it. Not sure what you mean about the drain since the dishwasher is not installed the drain should not be a problem. It is ALWAYS a poor floor installation when they do not put tile and/or laminate inside the opening so the ENTIRE floor is level. It would not have made the opening any higher, if they had, but if it does fit without legs, you DO need something to raise the floor under it so it has something to sit on.