All 240s from 1985 onwards use this 6-panel tail light. I think the later ones Volvo dropped that middle bulb on the bottom row and left a hole there. You can fit the style that has a bulb there and it will work fine.
There's two 6-panel designs, one has a chrome strip running between the two rows of lights, the other has a black strip. They are interchangeable, it is an aesthetic choice only.
If you need new lights, don't bother with Volvo genuine in this case, as they are just rebadged aftermarket lights and are not as good as the originals. You can get them all from Skandix.
In saying that, your lights probably do not need replacing. They look immaculate. These lights are notorious though, because the plugs don't make good contact with the flexible circuit board on the back of the lights.
Try jamming the brake pedal down or have someone press it while you jiggle the connectors behind each light and see if your brake lights come back. Alternatively try twisting the bulb sockets back and forth a couple times to see if that does it. They can be a real nuisance! Sometimes the prongs inside the connector need to be gently pushed together to improve the connection.
