That alternate A3 version is on the Alien Legacy collection...
Great for any movie fan. It comes in a very nice fold out box containing 9 DVDs, one special feature disc for each movie plus one more bonus disc. All 4 movies come with the alternate versions with cut footage or alternate scenes...
Personally, I thought the alternate A3 version made more sense, considering the size of the alien at birth and it explains what happens to a certain character, who seemed to disappear in the theatrical version. However, the theatrical version had the cooler ending...
Of course, no doubt that the extended version of Aliens was far superior to the theatrical...