Extra lightbulb on 81 tail/brake

Hey everyone,

Been a while but the '81 rescue is back on the schedule. I ran into something today I can't figure out. Thought maybe you could give me a reason.

On the backside of both rear tail/ brake lights, there is an extra bulb that faces inside the trunk cavity. I'm sure they have a purpose, I just can't figure out what it would be. Maybe a strange position for trunk lights? Ill post a pic if needed.

 

Thanks, I had a feeling.
My guess is, I must be missing some lenses that push into the holes that are in the tail light covers in the trunk compartment.

Im going to start digging. If anyone has a pic of that part, it would be very helpful.

So far it looks like I need two of these.

https://www.ebay.com/p/1138378748?iid=110651009698&chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=110651009698&targetid=860211358017&device=m&mktype=pla&googleloc=1014472&poi=&campaignid=6470661099&mkgroupid=89344977512&rlsatarget=pla-860211358017&abcId=1141156&merchantid=7871044&gclid=EAIaIQobChMI7JmmuJ605wIViLzACh3ujAyYEAQYASABEgLd5vD_BwE