IIRC there was a difference in the shape of the water tank, the kit you have appears to be the same as fitted to the Bedford MW. It was flatter with straight sides, the Morris was rounder in shape.
I stand to be corrected, but the photos I have of each seem to bear this out. The Morris was used early WWII, the Bedford appears to be used later on, on a much more frequent basis.
As I say, I am often reminded of my assumptions and errors, But I think the Morris should the more rounded profile.