I do believe you would need the "reflector" GM p/n 1674098 for the rectangular dome light with a single lense reading lamp. Problem is, the one-off design on the bulb holder gets brittle and breaks, and the thing is useless. The wiring is the same regardless of the lamp type you use. The plain white wire clip on the old dome light you want to remove as it's all kind of one piece. The white/red has a clip in wire with the rectangular lamp. Whether or not you can find one reasonably priced is a gamble. Junkyards are pretty much picked clean of 40 year old cars. Welcome to classic car ownership.
If originality isn't all that important to you, you can get one of those reproduction round dome lights and lenses. Same wiring, just need to transfer the dome lamp bulb end clips from your old one to the new one, and clip and cap/tape the switch end of the orange wire you don't need. I've never done that, so I'm not sure the mounting pins are the same.
GM p/n 20058837 clips for the front. Need 5. (original GM p/n 20088017)
GM p/n 20061050 clips for the rear. Need 3. The original arrow head design (p/n 20095324) got reconfigured later on as a different style rectangular looking clip, but it's effectively the same. PITA either way because there's no good way to get leverage in the position you need to get to for putting them in. Get some help putting those garnish moldings back in.
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