The model AGM-86 Air Launch Cruise Missile began life as a decoy missile, sort of an updated “Quail.” it was decided that the decoy could carry a nuclear warhead, and thus provide a lot more service; this began its development as a cruise missile. As originally envisaged, it had to fit in the some bays that could hold the AGM-69 SRAM missile; this made sense in a lot of ways but strictly limited its capabilities due to the short length. Efforts to increase the range of the missile included adding a droppable belly tank and stretching the fuselage for more internal fuel volume. The latter route was chose, along with making the nose much blunter and more voluminous.Both the external tank and the fuselage stretch meant that it could not long fit in internal SRAM bays, a tradeoff that was deemed worthwhile.
The illustration below dates from mid 1976 at the latest.
The full rez scan has been uploaded to the 2022-11 APR Extras folder on Dropbox for $4 and up APR Patrons/subscribers.