[Source: Airfix Mag Guide 27 - Modelling RAF Vehicles]
All in in 1/76 scale
Page 31 plan of Layland Subsidy A type, fuel truck
Page 39 Rolls-Royce armoured car early pattern
Page 40 Rolls-Royce Tender (1930 period)
Page 41 plan of Crossley 4 x 2 seater car
Page 44 plan of Crossley Tender
See also
http://www.landships.freeservers.com...lcan_et_al.htm for some early truck drawings. Also a number of others at
http://www.landships.freeservers.com/artillery.htm A little down the list to Softskins.