Led Zeppelin was known for releasing albums with unique record covers. In Through the Out Door was no exception, and for marketing purposes six different jackets were produced. They were sold with the covers inside of a brown paper bag sleeve, so unaware buyers wouldn’t realize which one they were purchasing. The hope was that sales would be increased, while collectors tried to obtain all six versions.
Here’s a couple more things about the record cover. Only on E Back and B Front, in the middle, below the license plates, can you see a small sign that says “Contains Lead” only readable on the LP covers, not the CD.