Drop-in resolution
Miyota 9015 vs Seiko NH35 (TMI NH35A): do they swap?
Whether the Miyota 9015 and Seiko NH35 (TMI NH35A) share a case, and what changes if you move between them.
Different footprints. The Miyota 9015 is 26.00 mm x 3.90 mm and the Seiko NH35 (TMI NH35A) 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 9015 is the slim premium Japanese automatic, a lower-cost slim alternative to the 2892 platform. The Seiko NH35 (TMI NH35A) is the default modding and microbrand automatic, hacking and hand-winding at low cost.
They differ in diameter (26.00 mm vs 27.40 mm), height (3.90 mm vs 5.32 mm), beat rate (28,800 A/h (4 Hz) vs 21,600 A/h (3 Hz)), winding behaviour. A slim 3.90 mm movement at 26.00 mm diameter that hacks and hand-winds. It shares its dial-foot pattern with the 9039, so the two interchange within a dial built for the 90 series.
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.