Funny, this 5-panel question was the interesting part of this post for me as well. I'd also be curious if the VIN matched. Folks often make model year mistakes as a result of the build date sticker, but those errors tend to go the other direction.

My understanding was 1983 saw the last of the 5-panels. We had an '83 DL sedan with 5-panels. Its owner's manual shows a drawing of both configurations, identifying the six-panel variety for GL, GLT, Turbo, and DL Canada. I also own two 83 (Turbos) with six-panel lights. Never heard of an 84 having 5-panel tail lights until this post. Wiring issues? Sure, they all had them.

One way I would distinguish an 83 from an 84 with LH2.0: Pull fuse 12. Does the engine die? It's an 83.
--
Art Benstein near Baltimore

Occam's Razor: That among competing hypotheses, the one with the fewest assumptions should be selected.