This is a picture of a 1999 Deville engine. It is the same engine but different module year but should be pretty much the same.
If you remove these plugs the spark plugs are underneath. You need a long extension and spark plug socket to get them out.
If you still can't find them, get a picture from the same position as this picture of your engine and I will show you where they are. Thanks
Image (Click to make bigger)
Thursday, June 18th, 2020 AT 8:09 AM