There are two screws, which should be behind the gasket around the headlight. One is on the side, it controls the left and right positioning and there is one on the bottom and it controls the up and down positioning.
there are two adjusting screws between the grill and core support. the lower one is for verticle and the upperone for horizontle adjustment. it takes a 4mm socket to do this.
Remove the 2 thumb screws that hold the headlight in place
In Australia, our Lumina is very similar to the Holden Commodore and the same screws fit them. The Holden Commodore is also a similar model to your Pontiac, because we have nearly the exact same design, so it light be an idea to check on that near your area.
first of all you need to take of screws on the coner of the bumper and the inside then under the bumper once you have done that there are 4 screws that hold the headlight on the bottom of the light on the passanger side it is easy to take off but on the driver side you need to go under the car between the radiator then you must unplug the headlight and it comes out i just did for my 95 it should be the same for 97.
on the carburetor
I think it has a hydraulic clutch and no adjustment.
Left side under the headlight assembly
There are two Torx adjusting screws, accessed through holes in the top of the black plastic housing...T23 I think. The center one adjusts up and down, the outside one adjusts left-right.
on the idepaent rear suspection for the parking brake
Remove the wiring harness from the back of the headlights. Remove the headlight retaining bolts. Remove the headlight. Reverse the process to install the new headlight.
Right behind the headlight on the passenger side.
In order to answer your question I will need the year of the car. 97