The P-38L was the most numerous variant of the Lightning, with 3,923 built and was the last model with modifications making it one of the best variants of the P-38. The P-38L was the first Lightning fitted with zero-length rocket launchers. The major upgrade was the presence of air brakes which aloowed a pull out of a dive much easier than prior models. Also "New Boosters" modules greatly improved roll-rate. These Lightnings also received the uprated V-1710-112/113 (F30R/L) engines, and this dramatically lowered the amount of engine failure problems experienced at high altitude so commonly associated with European operations.