Hanno,
Attached picture shows up in the NIMH archive; "Chevrolet C60L 3-tons 4x4-accumagazijnauto" (battery storage truck). I presume this is the 5F body. The spare wheel is more in line with the GS bodies fitted to the Dodge D60L, which also had the spare tyre under the right front corner of the body, presumably because of the longer civvy cab, when compared to the cab 11/12/13 cabs.
source:
https://nimh-beeldbank.defensie.nl/f...%22Foto%27s%22
Regarding the normal GS body and the long wheel wells and two positions.....
I seem to remember there was a description about this one of Bill Gregg's publications(?)........ and it had to do with the style of tyres; If a truck was fitted with Run Flat tyres, no spare was needed and the body could be mounted behind the cab directly. If it had normal tyres, the body could be mounted backwards leaving room for a spare tyre carrier behind the cab.