From Roger Freeman's "The Mighty Eigth War Manual": "The K-14 was the fighter version, first received for trial installation in July 1944 and progressively installed in as many fighter aircraft as possible after August, replacing all other types of sight. It was fitted on production P-47s from January. K-14A: From P-47D-35-RA P-47M."
Some Encounter Reports noting use of K-14 in P-47s.