There are three different versions of the V12 E-Type handbook, easily differentiated by the three different colour covers, and each of these three different versions have a number of different editions marginally updated to keep pace with slightly changing specification of V12 E-Type over life of model.
The White print on Light-Blue covered Handbook is issue number E.160 and came in four editions E.160/1, E.160/2, E.160/3 and E.160/4 with the E. prefix denoting English Language version, with /1 and /2 suiting all English markets including USA from 1971 introduction, but /3 and /4 no longer suiting USA market due to emissions and safety regulations introduced uniquely in USA. (E.160/2 is available as a Brooklands reproduction)
For 1973 USA MY cars a special USA only edition of V12 E-Type Handbook was published, with yellow print on a crimson cover issue/edition numbers A.173/1 and A.173/2 with the A. prefix denoting America version. The cover actually also includes “U.S.A. Specification” in wording.
For 1974 USA MY cars another special USA only edition was published, this time with with red print on a tan/yellow cover issue/edition numbers A.181/1 and A.181/2 (A.181/2 is available as a Brooklands reproduction)
Source: Roger Payne, forums.jag-lovers.com