[Wavytone]

Many thought so for a long time but apparently not the case - some on CN have discovered they are more-or-less interchangeable. There is some variation, of course, but its within being well worth trying.

It may also require some firm talking on your part to get just the corrector - it also appears Celestron does try to talk you into a set of primary, secondary and corrector plate.

Decades ago without modern computer-controlled grinding and polishing machines it probably was true that the optic sets were hand-matched at the factory, but not any more.

Secondly the machines are able to produce mirrors to the required shape within 1/8 wave without hand finishing. That is far better than the accuracy required for the figure on a lens - or a corrector plate. Hence correctors don't really need to matched to the mirrors anymore - they're randomly matched - which may also explain the "hand-picked" ones off the factory floor that are better than the rest which are within tolerance (however Celestron defines that), but not particularly perfect optically.