Plotting the relative lengths of the prop-shafts using the banjo axle flange as a datum point allows us to see the relative positions of the 3-synch non-OD and OD gearbox flanges. Then using those points as datums allows us to plot the relative positions of the Salisbury axle flange. That shows that the prop-shaft for the Salisbury and 3-synch OD option should actually be fractionally longer (circled in red), but the sliding joint is more than adequate to take account of this. It also allows us to measure the length of the prop-shaft required when a 4-synch gearbox is retro-fitted to an early car with a Banjo axle.