Help on Bedford MW details

[mudeng]

Hi,
Further to my earlier request about Bedford MW series, I note from the references I have so far, that earlier vehicles have a cut out on the bonnet side panels, later models have "slots", also, on both late and early patterns, the mesh grill was fitted on the outside as an oblong panel, and sometimes inside the front panel.
Is there any reason, or details of these various changes ?????

Thanks.

George.