I'm going to try and fix my buddy's 300SD for him if I can, #1 he admits it got low on transmission fluid but I don't know how long or how many miles it was low.

He described the problem as at first the car had problems shifting from 3rd to 4th, then it stopped shifting from 3rd to 4th, now it won't shift from 2nd to 3rd.

I've been studying on my '81 300CD, but they seem to be a little different. Does the '85 300SD shift from a vacuum as well?

Not sure what else to look for, he is supposed to get it brought over this week so I can check it out.