This Italian jet trainer was the successor of the MB326 and clearly has the same basic features. The MB339 also has straight, low mounted wings, narrow air intakes in the wing roots and the exhaust far beyond the vertical stabiliser. The aircraft sits close to the ground with its short landing gear. The main gear retracts outward, in the wings. Different is the tandem cockpit in which the instruc­tor in the back seat sits higher than the student pilot in the front. 

The different versions of the MB339 can externally be distinguished by

• the number of seats
• the presence of pylons under the wings, for storage of weapons or drop tanks
  
• the presence of a cannon at the side of the forward fuselage
  
• the presence of a refueling probe
• the presence and shape of of tip tanks

The three prototypes of the MB339 were designated MB339X. Externally, they appear not to differ from the first production version, called MB339A. Both versions have large but variable diameter tip tanks and two seats as recognition points. Each export version had a specific designation, namely MB339AM for Malaysia, MB339AN for Nigeria and MB339AP for Peru.

The Italian military designation for the MB339A is FT-339A.

Probably this version has underwing pylons, but is for the rest similar to the MB339A. However, just one was built, so it is guessing.

This is the more modern variant of the MB339. Externally, the main difference compared to the MB339A is in the tip tanks: these have a smaller and more constant diameter. It also has one or two removable pylons under each wing, so these are not always a recognition point. Internally, more has changed, including a digital cockpit. Subversions include the MB339CB (for New Zealand), MB339CE (for Eritrea) and MB339CM (for Malaysia). This version was also a contender in the JPATS competition in the United States, where it would have been known as Lockheed T-Bird II, hadn't it lost.

The Italian air force got an even better MB339C, with a fully digital cockpit and a fixed refueling probe at the side of the nose. The export version is known as MB339FD.

In Italian military service the MB339CD is called FT-339C.

Aermacchi tried it with a single seat light attack version of the MB339, but this MB339K did not succeed. Only one aircraft was built. Obviously, the single seat cockpit is the main distinctive feature, as are the cannons at the lower side of the fuselage, below the cockpit. Additionally, the MB339K has pylons under the wings, but no tip tanks.

Both in Italy and United Arab Emirates the MB339 is used by the aerial demonstration teams, called Frecce Tricolori and Al Fursan respectively. The MB339s are modified MB339As, called MB339PAN (for Pattuglia Acrobatica Nazionale) or AT-339A in Italy and MB339NAT (for National Aerobatic Team) in the UAE. They have no tip tanks but have smoke generators.

This is a version only used in Italy, for electronic calibration and electronic warfare. The designation MB339RM reflects this as "RM" stands for "radiomisure", or radio measurements. We don't know its characteristics, so if you know please inform us.