I just recently purchased a 1985 300tdt and have been fixing it up.
One of the issues was the sunroof. It worked very rough and squeeky. I was told that you need to use a lubricant that wont attract dirt and dust or you will be constantly cleaning & re-lubing it. After some internet research I came across Krytox. It is about $35 for a 1/2 ounce syringe. I used it on all the contact points on my manual sunroof. It only took a very small shot in each area and after a few operations to work it in was very good. The sunroof operates like new, very smooth and silent. It now takes about 25% of the effort to operate the sunroof. It was worth the price just for the sunroof and I still have an almost full syringe to lube all other friction points on the chassis.

Just thought I would pass on a tip for a great product.