All 6 taillight/brake light bulbs and the 2 license plate bulbs are replaceable by popping the socket out of the rear of the taillight housing from inside the trunk. They are just pressed fit into place. You do not have to remove the taillight housing to replace any of the bulbs.
Six tail light bulbs should be same. WCCC has a bulb chart -1157 for tail light. Might be good time to consider LED replacements? With these old cars hard to say why somebody has put wrong parts in but usually because they were cheap or didn’t know better.
There are 8 lights in the tail panel. From left to right looking at the rear of the car, there are the three left hand 1157 tail lights, then two #97 bulbs (one on each side of the license plate), then three more 1157 lights for the right hand signals. The license plate lights are just sockets you pull out just like the other 6 tail light bulbs.