I need a diagram on how to change a heater core in a 1994 cadilliac deville sedan?

the only place I know to get any type of diagram for the 94 Cadillac is from the original shop manual (not a Chilton's) that's usually given to shop mechanics at the dealership. However, you can buy one online or over the phone, but it may be a little pricey (between $70-$100 depending on condition). Check out Faxon Auto Literature (website below) and you might be able to get what you need. If they don't have it, they might be able to point you in the right direction to get one.