Well Clint
Text on the front says Kingman - 43 which indicates it was in use at that base in Arizona in 1943.
My knowledge about various training units in USA is next to nothing. The record card for this one is minute if Peter Marson is correct.
It was del to Harlingen, TX on 26.3.1943. Obviously transferred to Kingman at some point in 1943, but that's it.....
It is possible one can find more on the 'net but right now I am too tired.
Cheers
Stig
PS: There is another sale of the same post card, but without any further notes here
https://www.ebay.com/itm/Lockheed-AT....c101196.m2219
It actually looks like 42-55569 which in such a case went to Wright Field, OH on 10 Feb 1943
Except listing it as crashed Peter has no more details about that one either.