here's a picture of an original one
the ends are sheared at a slight angle
you can take a large bracket and cut it to look like this
turn the sheared end to the rear and it will look fine
it is 2 3/4 like Peter says
tom
I have several NOS 180A rear bumper crossbar spacers that are now available. Until reading this I knew what they were but did not know their the year and body style application.