Drop-in resolution
Miyota 90S5 vs Miyota 8200: do they swap?
Whether the Miyota 90S5 and Miyota 8200 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The Miyota 90S5 (26.00 mm x 3.90 mm) and Miyota 8200 (26.00 mm x 5.67 mm) are near in size but differ in height, dial feet or layout, so moving between them means a new dial, hands and often a case adjustment.
The Miyota 90S5 is the open-heart member of the 90 series, showing the balance through the dial. The Miyota 8200 is the no-date base of the 8200 family, in clean-dial entry automatics.
They differ in height (3.90 mm vs 5.67 mm), beat rate (28,800 A/h (4 Hz) vs 21,600 A/h (3 Hz)), calendar layout (open heart, no date vs centre seconds, no date), winding behaviour. A 90 series caliber at 26.00 mm x 3.90 mm with an open-heart aperture that exposes the balance. It shares the 9015 footprint and dial feet but needs a dial cut for the open-heart window.
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.