CUILOAD
If you are missing the IMPACT tabs in Autocad you might have to load them manually.
To do that you have to open a drawing in AutoCAD, type CUILOAD and press enter.
You will be presented with a popup window like this.
First of all, you have to remove all of the loaded groups that start with fx. PRECAST_
You do that by selecting the group and press the unload button (do that for all of the groups for precast).
When you have unloaded the Precast modules you press the browse button.
In the next window that will pop up, you scroll down to find the precast files and select one and press open
After you press open, press Load in the other window.
Do that for all of the precast groups.
When you have done that for all of the modules you can press close and all of the tabs should reappear in Autocad.