Drop-in resolution
Miyota 90S5 vs Miyota 9075: do they swap?
Whether the Miyota 90S5 and Miyota 9075 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 9075 (26.00 mm x 4.92 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 9075 is the Miyota true-GMT (traveller) automatic, in affordable GMT travel watches.
They differ in height (3.90 mm vs 4.92 mm), calendar layout (open heart, no date vs centre seconds, true GMT 24h hand, date at 3). 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.