I was looking for something else and tripped over the following, from the front of my (around 2005) manual
so my FG649E is (F) forward control, (G)diesel, 4wd, (6)wide cab, (4) gvm 6000-6900kg, (9) 4D34-T, (E) 2780mm wheelbase
char 1 Vehicle Type
F = forward control
char 2 Basic loading capacity, drive system, fuel
E = diesel engine, payload 2000 to 3500 kg, 4x2
G = diesel engine, payload 2000 to 3000 kg, 4x4
char 3 Cab style
5 = standard cab (1695mm)
6 = wide cab (1995mm)
char 4 vehicle variations suspension
3 = rigid axle light duty vehicle (payload 1500 to 3000 kg)
4 = rigid axle light duty vehicle (gvm 6000 to 6900 kg)
5 = rigid axle light duty vehicle (gvm 7000 kg or more)
char 5 engine
4 = 4M42T
9 = 4D34-T
char 6 wheelbase
FE
C = 2750mm
E = 3350mm
F = 3760mm
FG
C = 2530mm
E = 2780mm