Points of interest:

Similarities:

• Both the 3 register dials seem to be of the same construction, weight and designgn.
  
• "Swiss" is the same font and size
  
• Mounting lugs and holes all seem to be consistent/similar
  
• paint style seems to be similar: all have a raised/lacquered type paint

Differences:

• The "U" in Heuer in the shield logo somewhat different in that the blue dial has "pointy" "U" and the silver dial has a rounded "U" in the shield (have we seen any other examples of Heuers with this style logo?)
  
• The "4" in the sub register of the silver dial is "open" whilst the two blue ones are closed font "4".
  
• No luminous hour markers on the silver dial
  
• Pointed "A" in "MONACO" in the silver dial versus the flattened top of the "A" on the two blue examples
  
• The McQueen Monaco dial is the only one signed in the rear "Singer" (the other 3 regs are unsigned)
• "Heuer" on the silver dial in the shield logo is placed at the outer proximity of the shield, whilst the two blue dials have more of a "space" within the shield and the Heuer wording.
  
• Subdial graduations: one constant font thickness on the silver dial yet on the blue dials the major minute graduations are marked with a heavier font

Some apparent similarities and differences....

• Maybe the silver "square waffle" dial was a late series dial before production ended and Heuer were playing with different dial colours to
  spark late consumer interest?
  
• Maybe it is a Heuer service part produced post production to provide spare parts to dealers?
  
• To me, it looks like a genuine Heuer dial, although my only qualification is the difference in the Heuer shield logo....but maybe some other dials exist to show that the logo evolved over time (indeed as almost all consumer logo brands do)

Cheers to all

Stewart Kay