29.01.2009, 10:54
From the book "Profile Aircraft 255 Nakajima Ki-44 Shoki (Tojo)" it seems that the under cowling oil cooler was from Ki-44 Ib. But on Aircam 25 "Nakajima Ki-44 Shoki Ia, Ib, Ic/IIa, b, c in Japanese Army Air Force service" says (in a photo note): "Oil scoop was an identification feature of Model 2". So, this is not very clear, but there are other differences between I and II: The II had a streghtened landing gears and retractable tail wheel.