Hi Dick,
As far as I know the Chevrolet CMP Portees were only used in North Africa. Wheels & Tracks magazine features a picture of one converted into a gun tractor in use in Italy.
See
http://homepages.ihug.co.nz/~Sbarnes/portee/chev.html for some pictures of surviving Chev Portees.
Can you show us a picture of yours?
Thanks,
Hanno