The Keystone LB-7 was an LB-6 with different engines. The initial production LB-7 (S/N 29-388) was designated XLB-7 while undergoing prototype testing. It was later redesignated LB-7. Keystone named the aircraft Panther (the LB-6 was also named Panther), but the name was not adopted by the Army Air Corps.
Three LB-6 aircraft were re-engined late in their service lives to become LB-7s. One LB-7 was modified to become the XLB-8, and another became the XLB-9 after an engine change and a final modification resulted in the XLB-12.
TECHNICAL NOTES: Armament: Five .30-cal. machine guns and 2,000 pounds of bombs Engines: Two Pratt & Whitney R-1690-3 radials of 525 hp each Top speed: 114 mph at sea level Cruising speed: 95 mph Service ceiling: 11,650 ft. Range: 632 miles with full bomb load Span: 75 ft. 0 in. Length: 49 ft. 3 in. Height: 18 ft. 1 in. Weight: 13,070 lbs. gross Crew: Five Serial numbers: 28-388 to 28-395, 29-1 to 29-10 (Note: Three LB-6s were re-engined to the LB-7 configuration [29-13, 14, and 16]. LB-7 29-9 became the XLB-8. LB-7 29-10 became the XLB-9. LB-7 28-388 became the XLB-12.)