[jim sewell]

David I would say these are CCKW 's

There appears to be a observation turrent on the roof of the cab in the back ground, have not seen any pic's of ACKWX's with this.

ACKWX had the petrol tank under the seat , thus an external filler tube on the right hand side of the cab , the cab in the back ground does not show this.

ACKWX had a 5 stud wheel where as the CCKW had the 6 stud wheel , this is difficult to see in the picture shown.
The CCKW started production for the US Army in January 1941 and the X was dropped after 13,187 were produced.

Regards
Jim S.