From which pack?
I have a series of MD81's from CLS but they are payware there are several different variations.
some of the older aircraft are hard to find.
And be careful when downloading a plane that has a auto installer. In most cases things do not go where they belong.
I down loaded a B737-200 the other day and when I went to fly it there was not the first gauge in the panel. I later discovered the reason was the auto installer put the gauges in the same folder as the aircraft which is not where they are supposed to be. Once i moved them to where they belonged everything looked all right.
Just remember before installing anything make a backup as you will regret it if you do not.
All it takes is one bad install and it can cause all kinds of havoc because things do not get put where they belong.
Stick with trusted sites