Where are the spark plugs located on GMC Vandura?

You have to take the interior engine cover off to access the spark plugs.

First take out the two screws that hold the drink holder, Take all the Philips screws that hold the leather/covering, Remove two screws/bolts in ash tray compartment, then remove two bolts at the bottom front of engine cover, lastly unlatch both sides of the cover. The best way to remove the cover is to push the bottom toward the engine and pull the top out(away from engine) and up...it's tight.