Editing Keystone B-3 (section)

==Variants==
;LB-10
:The last of the 17 [[Keystone LB-6|LB-6]]s ordered (S/N 29-27) was converted with a re-designed single fin and rudder and two 525 hp Wright R-1750E engines.  Delivered to Wright Field on 7 July 1929, it was wrecked on 12 November 1929.
;LB-10A
:This version used Pratt and Whitney R-1690-3 Hornet engines and was slightly smaller, in both wingspan and length. A total of 63 were ordered (S/N 30-281/343).  All were re-designated as the B-3A before any deliveries were made, with the final 27 built as B-5A with Wright engines.
;B-3A
:Ordered as LB-10A, 36 delivered as B-3A (S/N 30-281/316). The first aircraft was delivered in October 1930.
;B-5A
:Ordered as B-3A, re-engined with [[Wright R-1750]]-3 Cyclone engines, 27 built (S/N 30-317/343).