d6 Star Wars and d6 Space Opera - A comparison in detail
West End Games, and their (now open source) D6 Space Opera
Note that there are a lot of differences between various rules editions, but not all rules editions had core rulebooks published.
I'm not allowing additions, but am allowing comments. This is a collation of several posts of mine from years ago on a couple different boards. It's done as a geeklist to make it findable in all the relevant editions. (A forum post wouldn't be.)
If I missed some relevant detail that changes, post a comment, and once I verify, I'll edit and add it.
- [+] Dice rolls