I have a 1973 240z and came across this knob located on the drivers right side. Anyone have any ideas? Thanks

Purely speculation but it looks like my aftermarket AC temperature knob.  Whats on the back side of it?  On my '74 260z theres just a bolt in that spot.

chiefmd,

I have a 72 Z which has the same knob you described and in the same location.  Mine operates as a dimmer switch for the dashlights.  Presumably, yours has the same function.  Hope this answered your question.

Old Hat

As Old Hat says, it's a instrument light dimmer switch, why anyone with a Datsun would want those lights dimmer is beyond me, can barley see them now.

I was thinking it might be a dimmer, just need to check it out. Thanks for all the input.

3 hours ago, grannyknot said:

why anyone with a Datsun would want those lights dimmer is beyond me, can barley see them now.

You got a nice dark location to put my car during the day? I'll show you my dash lights. You'll never be the same. 

52 minutes ago, Captain Obvious said:

You got a nice dark location to put my car during the day? I'll show you my dash lights. You'll never be the same. 

Dark places?  I'll show you mine?  Sounding a bit kinky. 

That's how I roll?