All the tail light bases have little pointed things that help locate the circuit board. Using a pre-1986 base with a 1986+ circuit board can work, but there are problems.

Cause is the lower outer lamps changed to 2-filaments and therefore need three contacts on the circuit board (ground, marker, brake).

On the driver's side, it's easy. The newer bulb holder fits into the keyed slots OK, but it won't turn far enough to lock and to make proper contact because the little pointy pins are in the way. Cut off one, or is it two?, make the cut spot very smooth, and the bulb holder will turn, lock, and work just fine. BTW it must be a BLACK bulb holder.

On the passenger's side, it's not so easy. The bulb holder can go into the keyed slots, and after cutting off the one or two pointy pins, it will turn and lock. BUT one of the contacts will be in the wrong place. It won't work.

My solution was to leave the keyed slots unchanged. The contact that's wrong is the one toward the center of the car. The outside one and the bottom one are OK.

I took a surplus bulb holder and trashed it. Cut off one of the contacts. When installed that little "bridge" contact fits sideways to the bulb holder contact that's "wrong".

Bulb holder contacts point from the bulb outwards, in a radial direction. The bridge points along the circumference of the bulb holder, in a tangential direction.

The bridge's square end - where it got cut off - ends up under the bulb holder contact (which holds it in place) and its' dimpled end ends up in contact with the "right" part of the circuit board.

How did I get it in place?

Take the piece you cut from the trashed bulb holder - that's the bridge - and put a very slight bend (like 5 degrees) across it about half way down its length. That bend will make the bulb holder contact exert a little more pressure on it.

Locate the spot on the circuit board where the bulb holder contact will be when turned and locked.

On that spot put a 1/4 inch square of double-sided 3M Scotch tape . Then put a 1/4 in square of the same tape on the square end, dimpled side, of the bridge. Store the remaining tape with your gift wrapping stuff, it's great for that.

Now's the tricky part. Put the bridge in place, sticky tape to sticks tape, so that the dimple is in contact with the "right" part of the circuit board, then while holding it in place, install, turn and lock the bulb holder. You must hold it in place tightly because the turning of the bulb holder will try to move it into the wrong position. I used a flat tip screwdriver to hold it.

The bulb holder must hold the bridge tightly enough so that vibration and potholes won't mess it up.

Result: Bulb holder contact no longer touches the "wrong" part of the circuit board, and in fact it is insulated from it by the two thicknesses of tape. Instead, that contact touches the bridge which reaches over and touches the "right" part of the circuit board.

Has worked for me several years. BTW - right side bulb holder must be WHITE.

Good luck, both with the job and with understanding this. Wish I could do a picture, but can't yet.

Bob

:>)