1800 examples of the P-39G (Bell Model 26) were ordered on August 21, 1941. Serials were 42-4244/5043 and 42-8727/9726. These aircraft were originally intended to be identical to the P-39D-2 except for the new Aeroproducts propeller. However, the P-39G underwent several modifications during the contract stage, leading to different suffix letters being applied as production progressed, and none were actually being delivered with the "G" suffix letter. At this time, the production-block suffix had not yet been introduced into the USAAF designation system, and these aircraft were, instead, delivered as P-39K, P-39L, P-39M, and P-39N.
For some reason, the suffix letter "H" was never assigned. The suffix letter "I" was never used in any case, since it could be confused with the number one.