Here's a good side by side comparison (photo below). Yours is definitely the slant six version. From my understanding, some '66's came with the drop links, but not all. My slant 6 '66 Dart came with the non-drop centerlink, but some slant cars had them.
Like RRR said though, you may not even need the drop version. Just depends on where the small block ends up sitting. You may be lucky - many others have been.
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