I am unsure of the specifics as well. What I know for certain is that some ended up not being used as originally intended and thus remained unfitted. They had storage compartments for tools in the tub, a foldable two section ladder on the roof, and a single foldable seat on the rear right hand wheel arch (same as on Series 1 FFW models with 24V electrics for radio operators).
If I can gather correctly from research, they were all painted in RAF blue-grey thus any yellow sprayed on their body to aid airfield visibility was done once delivered to their respective units. Of the known survivors I have managed to track down, all their hardtops were white/cream with no sign of yellow or blue-grey.
Those transferred to the Ministry of Public Buildings and Works (MPBW) were given FUV or FUL registrations. Unfortunately my reg was transferred at some point and is currently on an A-reg plate.