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.
The Gulfstream II is listed explicitly in Federal Register 78 FR 39576.
Any Gulfstream IIs that have not been modified by installing Stage 3 noise compliant engines or have not had “hushkits” installed for non-compliant engines will not be permitted to fly in the contiguous 48 states after December 31, 2015.
14 CFR §91.883 Special flight authorizations for jet airplanes weighing 75,000 pounds or less – lists special flight authorizations that may be granted for operation after December 31, 2015.
Gulfstream II (G-1159)
Twin-engine executive, corporate transport aircraft, with accommodation for up to 14 passengers, powered by two Rolls-Royce Spey RB.168 Mk 511-8 turbofan engines.
Gulfstream II TT
Modified version with tip tanks, increased range.
Gulfstream IIB (G-1159B)
Modified version, with the wider, wingleted wings and instruments of the Gulfstream III, Maximum take-off weight increased to 68,200 lb. or 69,700 lb.
Gulfstream II SP
Aircraft modified by the addition of Aviation Partners winglets.
VIP transport version for the US Coast Guard.