Ben,
I cannot find any frame numbers with a hyphon, such as 94-851 but if it is 94851 according to 'British Forces Motorcycles 1925 - 1945' by C.J. Orchard and S.J. Madden it was one ove 15,000 supplied between 24th September 1942 and 3rd November 1943 under contract S1048. That lot carried WD numbers 5115218 to 5130217.
Regards, Peter.
VMCC Triumph Specialist