[mrein3]

I vote transmission temp.

I put a quartz clock in the extra hole. Then I got a stereo that fits the uncut dash that has a clock so that quartz clock is of no use to me.

I have a transmission temp gauge mounted knee-knocker style. Some day when I have a bunch of time I'm going to put the trans temp in the 4th hole and get rid of that clock. I use tans temp all the time and never need the clock.

I will say however that those 80s clocks out of subs and pick-ups keep very good time.