The Grumman Gulfstream I turboprop was one of the the first designed as a dedicated corporate aircraft. As such it can be regarded as the largest bizprop ever built, because after that there were only big jets, and only smaller props like the Beech King Air and Pilatus PC-12.

Grumman's model G.159 has five big oval cabin windows on each side, the same as which are in the Gulfstream jets nowadays. The shape of the engine nacelles is similar to that of the HS748 and YS-11, with a ring-shaped are intake and a bulge below the wings to house the landing gear. The Rolls Royce Dart engines power four bladed props. The G-I has six flat cockpit windows.

The different versions of the Gulfstream I can be identified by:

• the length of the fuselage
• the shape of the nose
• the absence of cabin windows

The original corporate/executive transport was at first simply named Gulfstream, but this became Gulfstream I when the Gulfstream II jet appeared. It has all the features described above in the general section.

One such VIP Gulfstream I was operated by the US Coast Coast with designation VC-4A.

The Aviation Group held an STC for a full cargo conversion. It has a cargo door at the same place as the optional one on passenger G-Is and the cabin windows ave been replaced with metal plugs. It has no different designation nor marketing name.

When the US Navy required a 'flying classroom' to train navigators for the A-6 Intruder fighters, nine Gulfstream Is were acquired. They have a large nose, in which the radar of the Intruder was placed. Their official designation was TC-4C, with name Academe, although this was not used often.

While Grumman had tried to sell the G-I as commuter aircraft before, it did not succeed. Only after Gulfstream American had taken over, a stretched variant was offered. This Gulfstream IC, also reffered to as G.159C, has a 3.5 m longer fuselage with seven cabin windows on each side instead of five. Just five were converted from standard G-Is.