Are the speedometers in the V8 124s purely digital?
 

I was looking at the service cd's for something when I came across something else and in it refered to the V8 models as having a different method for dissconnection, mainly no cable. Anyone else think so?

Not digital but the drive comes from an electric motor in the spedo, similar to the W126 chassis.

The only reason for SPEEDO cables in any W124 chassis is the fact in Germany that that was the primary car for "taxi-cabs" & they needed yo use cables as electronic meters weren't ready for operation as they are now.

Question...

Is there a way you can modify the speedometer reading by (let's say) adding a resistor or something?

I changed the wheels and tires on my car (a bit bigger) and I think speedometer is off a bit.