I've done this, and it works. I grabbed an almost new circuit board and a good taillight with the pre-85 setup on it. There were a couple little pins or ridges to shave off. The board stuck on and lines up fine, and works right. In fact at the moment it's the only one (of 4) that has no "bulb out" light.

The taillight is indistinguishable other than finding one with a chrome or black trim strip to match your other one. For whatever reason the left ones seem to have more failures- I think the spare tire whacks the brake light socket. Also, if you ever change a bulb and it's all white and cloudy, you have a problem with water getting in the housing. Some small holes drilled in from the bottom corner will drain that out and prolong the useful life of your lights.

Good luck!
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total