Model 12A
Powered by two 450 hp (336 kW) Pratt & Whitney R-985 Wasp Junior SB radial engines.
70 built.

Model 12B
Like 12A, but powered by two 440 hp (328 kW) Wright R-975-E3 Whirlwind radial engines.
This was a normal civil model, but the only two built (serial numbers 1228 and 1249) went to the Argentine Army.

Model 12-25
Last two civilian Model 12's produced (serial numbers 1293 and 1294), same as 12A but with Pratt & Whitney R-985 Wasp Junior SB3 engines.
Model 12A
Powered by two 450 hp (336 kW) Pratt & Whitney R-985 Wasp Junior SB radial engines. 70 built.
Model 12B
Like 12A, but powered by two 440 hp (328 kW) Wright R-975-E3 Whirlwind radial engines. This was a normal civil model, but the only two built (serial numbers 1228 and 1249) went to the Argentine Army.
Model 12-25
Last two civilian Model 12's produced (serial numbers 1293 and 1294), same as 12A but with Pratt & Whitney R-985 Wasp Junior SB3 engines.
Lockheed Model 12 Electra Junior