I have a soft spot for Buckleys - I have three. Having Mills parts would be normal, as most were built that way, but the more desirable ones have Buckley parts, especially the mech, which resembles a Mills but is clearly different and easy to spot. The most notable feature are the dampers (sometimes 1, sometimes 2, I think) that are part of the mechanism, high on the front. Operators liked these simply because you could swap parts with Mills. Back doors are the same for a start. I strongly suspect the upper front casting is a replacement from a Mills machine, as originals always have 'Buckley' on the casting, as far as I know. They rarely have jackpots (at least showing).