 P-51Ds without fuselage fuel tanks were fitted with either the SCR-522-A or SCR-274-N Command Radio sets and SCR-695-A, or SCR-515 radio transmitters, as well as an AN/APS-13 rear-warning set; P-51Ds and Ks with fuselage tanks used the SCR-522-A and AN/APS-13 only.The P-51D became the most widely produced variant of the Mustang.A Dallas-built version of the P-51D, designated the P-51K, was equipped with an diameter Aeroproducts propeller in place of the Hamilton Standard propeller.