[gmc684x4]

Looking at your headlight bucket placement suggests its not a 67 68 possibly a 69 to 72

My only 68 I have is a Gmc so I can not use that as a measurement to see if the headlight bucket shifts on the 69 72 rad supports

Left pic is a 67 68 rad support and the right pic is a 69 72 support

you can see the 67 68 are a nice round backing area where the 69 72 are more off centre keystone shape