I think the 85 is set up the same as the 83. If so there is a way to do it without taking the turbo off but just from reading the way to do it it looks like a royal PIA to do. There is no elbow on the 83, the drain pipe goes straight down into the top of the oil pan. (do a search for turbo drain seal)
To do it from the bottom requires that you remove the oil pan and work from under the car. Doing it from the top allows you to repalce all the seals.