Just FYI, make sure your measurements come from a 70-71 car. On those cars the reverse light is positioned in such a way so as to leave room for the optional seat belt light.

72-74 cars have the seat belt light standard up by the instrument cluster, and because of this the reverse light on those cars is located in a slightly different spot.

You'd probably never notice just looking at it, but if you measure, there is definitely a difference.

Tav

P.S. I'm looking for the diameter of the firewall hole for this same light. I know where the hole goes, just looking for its diameter. 1970 only please. 71 uses a different size grommet.