Drop-in resolution
Seiko NH35 (TMI NH35A) vs Miyota 82S7: do they swap?
Whether the Seiko NH35 (TMI NH35A) and Miyota 82S7 share a case, and what changes if you move between them.
Different footprints. The Seiko NH35 (TMI NH35A) is 27.40 mm x 5.32 mm and the Miyota 82S7 is 26.00 mm x 5.67 mm, so they do not share a case. This is a choice between platforms, not a swap.
The Seiko NH35 (TMI NH35A) is the default modding and microbrand automatic, hacking and hand-winding at low cost. The Miyota 82S7 is the fullest 82S member, adding a 24-hour or day/night indicator at 9.
They differ in diameter (27.40 mm vs 26.00 mm), height (5.32 mm vs 5.67 mm), calendar layout (centre seconds, date at 3 vs small seconds, open heart, 24h at 9, no date), winding behaviour. Larger than the Swiss core at 27.40 mm, so it will not drop into a case cut for a 25.60 mm ETA. It is the unbranded version of the Seiko 4R35 and shares that caliber's footprint and stem.
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.