Thats the problem with referance material isn't. The more you have the more confuseing it gets. I have the Nut & Bolts 13, i didn't bother getting the 25 as i had already built a Kugel blitz by that point and didn't think 25 would have anything new. 13 just has pics of the prototype, with 1 of an un zimmed production wehicle.
As for PT, this is what it says about Ostwind production. I had to read it several times my self as at first i thought it was saying some were built on older hulls.
In addition to the rebuilt Pz IV chassis used at Ostbau, (i.e the prototype) at Stahlindustrie Ostwind turrets were to be mounted on newly produced Pz IV chassis.
Then it goes on to say production was to begin in Nov. Of course this implies un zimmed Ausf J hulls. But it confuses the matter by showing a table which shows Wirbelwind/Ostwind production by month on Re built chassis. I have noticed this a couple of times with PT with tables conflicting with text.
Think i better get that N&B 25.
I am a Norfolk man and i glory in being so
On the bench: Airfix 1/72nd Harrier GR.3/Fujimi 1/72nd Ju 87D-3