Type/Models:
    G91R and Y - Single seat tactical recon fighter
    G91T - Two seat weapon trainer
    G91PAN - Single seat aerobatic display fighter
Origin: Fiat (Aeritalia)
First Flight:
    Prototype: August 9, 1956
    G91R: December 1958
    G91Y): December 27, 1966
Final Delivery:N/A
Powerplant:
G91R, T and PAN:
Rolls-Royce Orpheus 80302 single-shaft turbojet
Thrust: 5,000 lb. (2268 kg.)

G91Y: Two General Electric J85-13A Single-shaft augmented turbo-jets
Thrust (Each): 4,080 lb (1850 kg) with full afterburner
Dimensions:
Wing span:
    G91R, T & PAN: 8.57m (28 ft. 1 in.)
    G91Y: 9.01m (29 ft. 6½ in.)
Wing Surface Area: 176.74 sq. ft. (16.42m²)
Length:
    G91R & PAN: 10.31m (33 ft. 9¼ in.)
    G91T & Y: 11.67m (38 ft. 3½ in.)
Height:
    G91R & PAN: 4m (13 ft. 1½ in.)
    G91T & Y: 4.43m (15 ft. 6 in.)
Stabilizer Span: N/A

Weights:
Empty:
    G91R: 3,300 kg (7,275 lbs.)
    G91Y: 3,900 kg (8,598 lbs.)
Loaded:
    G91R: 5,695 kg (12,500 lbs.)
    G91Y: 8,700 kg (19,180 lbs.)
   Performance:
Maximum Speed:
    G91R: 675mph (1086kph)
    G91Y: 690mph (1110kph)
Initial Climb:
    G91R: 6,000 ft. (1829m) per minute
    G91Y: 17,000 ft. (5180m) per minute
Service Ceiling:
    G91R: 43,000 ft. (13106m)
    G91Y: 41,000 ft. (12500m)
Combat Radius At Sea Level:
    G91R: 196 Miles (315km)
    G91Y: 372 Miles (600km)
Ferry Range:
    G91R: 1,150 Miles (1850km)
    G91Y: 2,175 Miles (3500km)
Armament:
G91R/1:
Four 0.5 in. Colt-Browning machine guns
Ammunition: 300 Rounds for each gun

G91R/3:
Two DEFA 552 Cannon
Ammunition: 125 Rounds for each gun

G91Y:
Two DEFA 552 Cannon
Ammunition: 125 Rounds for each gun

Bomb Load:
G91R/1:
Underwing racks for ordnance up to 500 lb (227 kg)

G91R/3:
Underwing racks for ordnance up to 1000 lb (454 kg)

G91Y:
Underwing racks for ordnance up to 4000 lb (1814 kg)
Notes:
In response to a 1953 NATO specification for a light strike fighter having rough field capability yet still be capable of 0.92 mach, Fiat proposed the F-86 Sabre inspired G-91. Despite the loss of the prototype on it's first flight, an accident which would cause the French to refuse to purchase the aircraft, the G91 entered production for the Italian air force. While the design was intened to be used by all the NATO coutries, only Italy and Germany eventually acquired the design.
98 G91R/1 , 1A and 1B plus 76 G91T/1 were procured by Italy. Germany acquired 50 R/3, 44 T/3 and 50 R/4 while a further 294 were built by Messerschmitt (later MBB), Heinkel (later VFW-Fokker), and Dornier.

Sources:
The Complete Encyclodepia of World Aircraft, 1997, Barnes & Nobles Books, ISBN: 0 7607 0592 5