This is a heavily-reworked Revell 1/72 Elco PT Boat, in the markings of - what else? - Lt.j.g. John F. Kennedy's PT 109.
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Except for the main hull, deck and deckhouses, everything has been either modified or scratchbuilt. The 37 mm deck gun - well documented in words and marginally so in photos - is a reworked Hasegawa anti-tank gun mounted on scratchbuilt lumber and with thread tiedowns.
Torpedo tubes were reworked from the original four-piece assemblies into roughly 30-piece tubes each.
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The .50 cal. MG mounts were also rebuilt with ammo chutes, detailed gun breeches and assorted other details.
Scratchbuilt depth charge racks, detailed engine mufflers and a correct paint scheme and correct (rough) deckhouse boat numbers round out the model.