Drop-in resolution
Miyota 82S7 vs Seiko 4R34: do they swap?
Whether the Miyota 82S7 and Seiko 4R34 share a case, and what changes if you move between them.
Different footprints. The Miyota 82S7 is 26.00 mm x 5.67 mm and the Seiko 4R34 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 82S7 is the fullest 82S member, adding a 24-hour or day/night indicator at 9. The Seiko 4R34 is the branded Seiko caller-GMT automatic, the retail version of the NH34.
They differ in diameter (26.00 mm vs 27.40 mm), height (5.67 mm vs 5.32 mm), calendar layout (small seconds, open heart, 24h at 9, no date vs centre seconds, GMT 24h hand, date at 3), winding behaviour. An 8200-family open-heart caliber at 26.00 mm x 5.67 mm with small seconds and a 24-hour indicator at 9. It shares the family footprint with the 82S5 but adds the 24h register, so it needs its own dial.
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.