The 3rd DIY was the left rear light that had gone murky due to the carbons from the exhaust of the diesel engine. Remember these are the original lights that are 30+ years old and the left rear started getting murky some 5-6 years ago to the extent that its time to get it fixed or replaced.
2 tabs and the back cover and bulb holder pop out.
6 x 8mm bolts and 2 push tabs and the reflectors pop out. Simply push on the edges of the lens and they come off along with the rubber seal.
I took both the lights off to replace the rubber seals and clean any dirt from the insides. The seal on the left light had a tear in it and i would find water on the spare wheel cover everytime I used to wash the car. Thankfully there isnt any rust in the trunk ( after removal of all the plastic trim inside ) or the body near the light.
Can't say the same for the light. The carbon deposit has definitely had its toll on the light and while the lens has somewhat become better, it wont be crystal clear. The only option is to get a replacement tail light.