If you Google for images, it's really hard to tell. My initial guess from those images would be the GL trim got the chrome strip and the DL got the black strip. You might expect the GLT to get the GL trim, but I'm seeing mostly black strip. Turbos often got sexier black trim, not princess platinum chrome trim. I see other images with both present on the rear, not surprising after all these years. Unless I was looking carefully like now, I never would have noticed the mismatch.

I would not want to overly trust eBay, Amazon or aftermarket listings on this trim question unless they seem authoritative of all years and the trim levels available in those years

I imagine a glossy dealer brochure from that year might be more definitive. I tried checking on the Volvo customer support owner manual area and there's no useful material.

I just remembered I've got an '85 brochure I tripped over the other week. I've now carefully checked it with a magnifier. It's all side views so difficult to tell from just the wraparound taillight portion, but it appears it's as I stated for the DL and GLT, both black strip. The GL isn't a good image for lighting at that end, but if I had to guess, again I'd say chrome strip is more likely, but could also be black strip if there was light reflection making it look brighter.

I also just hit on a 1987 Danish brochure. The GL badge is definitely chrome strip, as above, no other rear ends shown.

I would suggest matching taillights is all you need to worry about unless you're being ultra picky. If you've got a DL, definitely don't sweat it. You could always black paint a chrome strip one to match.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now