Immediately after Hellenic Kingdom entered NATO in 1949, US assistance started. Among the first aircraft given where several ex-USN Consolidated PB4Y and about 50-60 Douglas C-47. Some more PB4Y acquired in 1950's, raising its number to 20 airframes. The new squadron of Royal Hellenic Naval Aviation, 353th Naval Squadron was created to operate the PB4Y, with 12 airframes in service, rest 8 dismantled for spares. They serve almost unchanged until late 1950's, when RHN decide to upgrade to their systems.
Already from 1954, MARAC Electronics had started to work on a maritime reconnaissance radar, designated M51, capable of detecting enemy surface ships and surfaced submarines for the PB4Y. The aircraft could hit itself submarines with depth charges and torpedoes and for surface ships cooperated with fighters equipped with rockets. The M51 radar was placed in the nose of an retired RHAF B-24 Liberator (in my scenario RHAF used Liberators in WW2 and post war until mid 1950's) for testing. Tests were successful and in late 1960 first PB4Y-M was ready for service. Inside, several electronics form HU-16 Albatross and P-2 Neptune were installed, replacing the WW2 era systems. Also the roof gun turrets were removed and engines were upgated to HU-16 spec, developing now 1425hp each. Although the PB4Y-M did not had MAD (as the TN P5M Marlins), it was far superior than before. The M51 had also a limited capability of detecting large fighters or transport aircraft, with is antenna positioned horizontal instead of downwards and this capability led to the ill-fated AEW radar M291, developed in 1970's. But this is another story and involves the Bristol Britannia.
RHN PB4Ys very early in their career were called to real action for Korean War. Sadly, from 4 airframes went in Korea one never return back.
PB4Y were stationed also in Messimvria Naval Base in Black Sea since early 1950's and those were destined to be the last PB4Y in service, until well into the 1970's. A PB4Y-M modified to test platform for the Navy and flied for several more years in that role. Today only 2 PB4Y survive, one was downgraded to original set up and the other remained in -M spec (the ex-test platform). Most airframes retained the characteristic "USN Blue" color in their career and only a handful repainted to light grey similar with P-3H Orion in 1970's. The 353th Naval Squadron today has in service the P-3H Orion Mk2.
For creating the radar dome, I used the nose radar from the Argentine L-188 Electra as design base, creating a new dome for the PB4Y (which came from the ROCAF one).