For those still seeking information on the General Ability Index (GAI) and its components, these online documents may be of interest.

Many families find the information on indexes and subtests at wrightslaw helpful:
http://www.wrightslaw.com/advoc/articles/tests_measurements.html

Also this Pearson 49-page PDF file, easily found online, "The What, When, and How of the Wechsler General Ability Index" with a quick summary of indexes and subtests on pages 9-12:
http://images.pearsonclinical.com/images/Products/Wechsler/Wechsler_GAI.pdf

Another Pearson document easily found online (14 pages) discusses WISC-IV clinical interpretation and looks in detail at FSIQ, Indexes, Subtests, Items, and Task Components: