Only the very late edition Whizzers used the digital tachometer [CDI is also digital]. Sadly tthe majority of the tachometers currently in stock are the digital version. A large majority currently for sale were "take-offs" from the Ambassador II that were parted out. I would guess any ordered from Taiwan would be digital, as would most of Whizzer USA stock. All 2008 & later NE-r and Ambassador II models used the digital tachometer.
All models from 1999 to 2007 used and analog CDI and Analog tachometer. There were 3 versions of the analog tachometer, a plastic version [mate to the black plastic speedometer mentioned in this post], a metal cased unit with a dark face [mate to the metal black faced speedometer], and the metal cased white face [mate to the metal cased white faced speedometer].
Only one digital tackometer, and it is metal cased with a white face.
Bad News! No way to tell the difference between the digital and the white face analog version.
If you connect a digital Whizzer tachometer to an earlier analog system it just won't work correctly, and will be obvious. Some just act completely dead, while others will produce extreme readings at idle [6000 at idle, etc].
Hope this information is helpful.
Have fun,