The 50 R/4 that followed were identical to the R/3 other than in terms of armament. It had more powerful armament, added two wing hardpoints, and improved avionics compared to the Italian G.91 R-1s. The G.91 R/3 was the primary West German variant of the Fiat-made light fighter, with 50 built in Italy and another 294 under license in West Germany.
