Original 1964 Radio Fitment Question

[Uncle Mike]

I bought a 1964 Radio at a swap meet for my 65. I've put a couple original radios in other 64-66's in the past but running into this issue. When I put the radio in the dash the post on the right side isn't long enough for the nut to get onto. Why would this be different? I have attached a couple photos and circled the posts. How would I remedy this situation? Also are all these knob components original?

Any help would be appreciated,

Thanks