How do you replace tail light bulbs on a 3000GT?

When you take off the square plastic covers, the only bulb that you can access is for the backup lights. In order to get to the tail light, and turn signal bulbs you have to remove the assembly. Just unscrew the 4 nuts from behind the trim and very carefully pop out the assembly. If it is difficult to remove, you may have to loosen the screws that hold the spoiler. The 2057 bulb is the replacement. Hope this helps.  

Answer

i am assuming that you are asking about the 3000gt brake lights. well here it is for 91-99 all models 3000gt`s replacing the brake lights is very easy with the back hatch open stand against the rear bumper of the vehicle and look down in the trunk area,on the interior plastic covers/trim there are 4 little bolts that you turn by hand(they are made of plastic)remove the square plastic covers from the trim and look inside(behind the trim)and you should see/feel two light build harnesses there is 2 per side on the 3000 gt twist them and pull the bulbs out they should be cheap and easily found in any parts store
I will add this for the Dodge Stealth: Same as above to get behind the trim ... but you can not access the bulb sockets on the Stealth ... you must find the 2 10mm nuts that hold the tail light assembly on and remove them. Pull the assembly away from the rear of the car and then you can access the bulb sockets. The stop light bulb is a 2057 as indicated above.