R4M asks:
Can you tell me when did the bubbletop P47 turn into something common?By February '44, the razorbacks were no longer being produced at Republic's Farmingdale plant. In
P-47 Thunderbolt: From Seversky to Victory, Warren Bodie wrote that the first P-47D-25-RE rolled out of the Farmingdale plant of Republic Aviation on February 3, 1944.[p. 250] 385 D-25s and 611 D-27s had been completed by
6 May 1944. [p. 247] There's a great photo on page 264 of Gabby's D-25 with the following caption:
"Everyone subject to orders issued by Hq. at WIDEWING would certainly have removed the invasion stripes atop wings and fuselages within 7 to 10 days after D-Day. If anyone still doubts that bubble-canopy P-47Ds were then operational, here is Lt. Col. Gabreski heading out for what probably was a D-Day mission (freshly painted stripes,
over and under) on June 6 in his new P-47D-25-RE. The airplane had been painted by the 56th FG or the 33rd Service Group maintenance people and the pilot had certainly checked out in the newest model, all of which took time."
In another fine book,
Beware the Thunderbolt, David McLaren writes that the first D-25s (dubbed "Superbolts"

) were in
combat operation with the 56th FG on May 19, 1944. By June 1944, the 56th FG was flying a mixed bag of aircraft, ranging from the razorback D-22 and D-23 to the
D-28. Does that give you any indication how fast these puppies were being cranked out and sent into battle?
Certainly, most P-47s operating during this timeframe were indeed razorbacks, but it definitely wasn't in your words "almost all" of them. All new planes coming into the theatre would be bubbletops. I'd be interested to know in what book you read that.
Nevertheless, the point of all this drivel is merely to say that the D-25 is not a "late 44" plane. Again, there were only 385 D-25s made, which all went into service in May or June of 44. How "the D25 became common after the summer of 1944" does not compute if they were already in combat service and no more were ever built.