replace spark plugs on 1991 Cadillac DeVille

what do i need to do to replace sparks in rear.I relize its hard but any special tools or advise.thku

Asked by for the 1991 Cadillac DeVille
The most important tool, and I am being serious, is patience. You may also need a universal spark plug socket to get access at a better angle
I agree with the above and also maybe start contortionist training. ;)