You might want to give Performance Years a call (1-800-542-7278).
While they say that 70 uses a three-prong unit, they list a two-prong unit (Part # GME45) that would seem to be applicable for 70-72? You might want to get clarification/verification ... and find out what the third prong is for. This might work for you.
Rockauto also sells a two-prong for cars w/lights (not gauges).
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