Drop-in resolution
Miyota 82S0 vs Seiko NH70 (TMI NH70A): do they swap?
Whether the Miyota 82S0 and Seiko NH70 (TMI NH70A) share a case, and what changes if you move between them.
Different footprints. The Miyota 82S0 is 26.00 mm x 5.67 mm and the Seiko NH70 (TMI NH70A) is 27.40 mm x 5.32 mm, so they do not share a case. This is a choice between platforms, not a swap.
The Miyota 82S0 is the open-heart 8200 member with a skeletonised balance aperture at 7. The Seiko NH70 (TMI NH70A) is the fully skeletonised member of the NH3x family, in open-worked mod watches.
They differ in diameter (26.00 mm vs 27.40 mm), height (5.67 mm vs 5.32 mm), calendar layout (centre seconds, open heart at 7, no date vs full skeleton, no date, no seconds hand), winding behaviour. An 8200-family caliber at 26.00 mm x 5.67 mm with an open-heart aperture exposing the balance at 7. It shares the 8215 footprint but needs a dial cut for the open-heart window; the 82S5 and 82S7 are its small-seconds relatives.
Matching diameter and height is necessary but not sufficient. A donor is only a true drop-in when the dial-foot positions, hand-hole sizes, stem length and calendar layout also match. Two movements can share a case and still need a new dial, re-broached hands or a cut-to-length stem.