Range/Cook top = Should be located in the door area or on the frame around the edge where the door closes. For older ranges and stand alone cook tops, the model number should be located either underneath the cook top below the elements. Some cook tops will require you to look underneath the countertop. The side portion of the bottom frame is a popular place for new smooth top cook tops.  

Refrigerator = Check around the door area. Many are located on the interior panels inside the refrigerator and freezer. Some can be located behind the grille on the bottom of the refrigerator.

Washer = Check under the lid area. On Sears/Kenmore washers, check under the lid towards the back of the frame area. Almost right above where the water comes out. Other brands put the model number on the backside or top of the control panel. May also want to check the side panels of the washer

Dryer = Most are located on the door or on the frame where the door closes. May also be located on the back of the control console or on the side panel of the dryer.

Dishwasher = Check around the door area. Most are mounted to the tub around the latch area or the side wall.