The Lockheed 14 "Super Electra" (prewar BA had a few) had twin fins per the smaller L-10 Electra. A few years later the 14 was stretched to create the L-18 Lodestar. Riding in the aft cabin of the prototype stretched aircraft, one could feel the prop blade wake frequency striking the tail surfaces, so to prevent this, the entire tail was raised 12 inches - thus the up-swept aft fuselage.
Production model - Lockheed 18 (USAAF C-60) Lodestar:
Lockheed 14 Super Electra of LOT :
