HQ Sandman Speedo's

[Absinth]

So none are the QW QM QK QX RD that HQ1837 posted so I assume they are the GTS speedo codes.

If they are in order then:
QW is Fuel/Oil gauge
QM is the Tacho
QK possibly optional clock
QX is the speedo
RD is Temp/Battery

8/74 HQ, its KM/H and MPH. ?

If it's a 200kph/120mph it would be a Spare parts replacement speedo. I see in one of your pics on the SS site you have a Oct 79 Temp/Battery gauge.