I just changed the glow plugs on my 85/300TDT. I am not much of a mechanic, but I managed to do it and the car started first try! I wanted to tell other novice mechanics like myself that it is not that hard. I took the fuel lines off with a 17 mm wrench, I think that you have to remove them. Even with the lines off the last plug is tough to get at. To reattach, I put the all the lines on finger tight first, then tightened the bottom nuts, cranked it over a bit to try and get some of the air out of the lines, then tightened the top.

Peter