There are several changes between the 1977 and 1981 editions. The damage value change is probably the biggest (and was obviously necessary due to the way the damage/hp system works -- if you're applying each die to a different stat how do you factor in a "-8"?) but some others that come to mind -- scouts don't get 2 skills/term, there's no "optional survival rule," and there was a chart in Book 3 for determining trade routes based on distance and starport type (I never used this system, but it looks like it would generate LOTS of trade routes, which would be a hassle to keep track of on a map). Also, the 1977 version doesn't have the "TAS Form 2" character sheet (obviously, since that sheet contains spaces for info from Book 4 -- decorations, equipment qualified on, etc.). If anyone has (or wants to do) a consolidated list of changes I'd love to see it (hint, hint)...