The whole idea behind the "PorBoy" Gauge pictured at the top was for savings of money. I had all the parts already:
2" VDO Gauge in My Center Console.
Calibrated Temp Sensor to the VDO gauge
Stock 1975 Fuel cluster
Wire
The needed extra 1975 Stock Red Blinker/Fuel Gauge cluster goes for around $20.00. So for 20 bucks and some time you can have a Temp Gauge in the fuel cluster.
I have noticed that any gauge 'PRE 75' will need to be drilled. Only the 1975 and 1976 914 fuel cluster gauges have the fuel sender plate part you need that is a direct fit to the new VDO Gauges.
Here is my original post at the pelican site on my idea for the gauge:
PorBoy Temp Gauge InformationI hope that helps a little,