Seems like a good deal for $900 ... and it looks like the rear is fine in your pics.
I'm going to kick some tires myself this coming Tuesday evening. I met the original owner of a 1985 300CD yesterday and he asked if I wanted to buy it as it's his 3rd car and it doesn't get out much anymore. I looked it over at the gas station where I introduced myself, but I want to check it more thoroughly and let my wife drive it since it would be her daily driver. From what I saw so far it looks minty.