Hi Ken,
Thanks Ken. Your reply may have pointed me in the right direction.
The attached link to the HCVC shows a IH AB 120 with a very similar top. Not Army, but part of the National Mapping Agency. Perhaps this will help bring out another photo of an Army AB 120. I could not find one during a short Google search.
Cannot say it is exactly like mine but the proportions looks very similar even if the side flaps are different.
It is rather ironic in that my family owned a 1962 IH C120 4x4 Travelall Wagon when I was a boy in the USA. A huge 4 x 4 wagon in its day compared to Jeeps and IH Scouts.
Will look forward to seeing the dimensions of your AT4.
Cheers,
https://www.hcvc.com.au/forum/truck_...-120-4x4-story