The basic airfoils for the main area of the wing are similar to those of the Grumman A-6 Intruder aircraft and utilize NACA 6-series thickness distributions combined with an in-house mean line.

A buffet boundary commensurate with the M=.85 speed capability was attained by incorporating a row of co-rotating vortex generators on the outer wing panel.

Stall initiation on the basic wing was found to occur at midspan but spread rapidly to the tip, particularly at large flap deflections.

[3] During installation of the Aviation Partners Inc. winglets (as the G-IISP), the vortex generators and midspan fence were removed and replaced with six leading edge vortilons similar to those found on the Gulfstream IV.

[4] In 2013, the FAA modified 14 CFR part 91 rules to prohibit the operation of jets weighing 75,000 pounds or less that are not stage 3 noise compliant after December 31, 2015.

Grumman had delivered over 150 turboprop Gulfstream Is by the start of 1965 but were gaining competition from the jet powered Lockheed Jetstar, Hawker Siddeley HS.125, Dassault Falcon 20 and the North American Sabreliner.

The Gulfstream IIs were produced as green aircraft and delivered to a completion centre to fit the bespoke interior and avionics as required by the customer.

[14] A G-II (N105TB, cn 31) had underwing pylons and various fuselage appendages added to enable it to operate as a sensor testbed for MIT Lincoln Labs.

[17] A G-IIB (N178B, cn 125) was modified by the addition of a large dorsal fairing housing a telescope by Aeromet as the HALO2 aircraft for the Missile Defense Agency.

[18] A G-II (N10123, cn 107) had tip tanks added containing ground mapping radar, along with fairings on the wing undersurface and a centerline pod.

The aircraft had a nacelle added to the left wing, containing a 6000 hp Allison 570 turboprop engine (derived from the XT701 turboshaft developed for the Boeing Vertol XCH-62 program), powering a 9-foot diameter Hamilton Standard SR-7 propfan.

[25] A G-IISP (N510AG, cn 159) is operated by the Orion Air Group in support Northrop Grumman's development of the multi-role, tactical-command data link (MR-TCDL).

[26][27] A G-II TT (N81RR, cn 246) is being modified for NASA, by the addition of fuselage appendages and underwing pylons, to serve as the High Ice Water Content (HIWC) sampling aircraft.