To start with, the F4U-1 built by Chance Vought became the Corsair I. There were only 70 Corsair I's built, JT100-JT169. Sometimes referred to as F4U-1B (not sure what documentation shows this)?
I can't find all of the documentation to back this up, but I believe the Corsair I's were built with full span wings, making them useless for British carriers.
I did read that the first aircraft to have the short wing incorporated was JT270.
Unless JT-100/169 were retrofitted, use as training aircraft could be correct.
Here are some pics showing Corsair I's ( I believe in Maine, USA.) with the full span wing.
http://www.historylink101.com/ww2_na...149/15126.html
http://www.historylink101.com/ww2_na...999/15978.html
As to differences between the Corsair I and F4U-1, I haven't found anything major, especially if they had the full span wings. Perhaps the radios or some other small items?
The RNZAF did receive Corsairs, but these were US NAVY aircraft that were transferred. I have never seen anything referring to a "special build" Corsair for N.Z..
Regards,
Mike