which temp sensor

[2ndCIB]

I put summit vortec heads on my 350. When I went to swap over the sensors in the head they were the wrong size. The vortecs looks to have 3/8 and the stock head had 1/2 sensors. What is the best way to make this work? New sensor reccomendations? Its a 72, 350 with gauges. It has two sensors, driver front and passenger rear. Which is which? I think the driver front is for the gauge and the passenger is rear is for an idiot light. But there I go thinking again.