Ive been looking at the threads on modifying a 64 core support for a 66.

It is confusing because my support looks different and there aren't any other 65/66's around here for me to look at.

Today I got a chance to look under the hood of a 65 that is for sale. The bracket on the driver side of the support near the top is missing on my support. In fact it looks like one was never there.

I have a replacement radiator installed by the PO.

 

If theres no radiator brackets on the support and they part of the radiator then its a '66. The 66 is smooth. Just the inner fender. In your other thread I put a pic showing the difference between a 64 & 65
Charlie

 

1965 F100/250 2WD is not the same radiator support as 1966 F100/250 2WD