Drop-in resolution
Miyota 9015 vs Miyota 9039: do they swap?
Whether the Miyota 9015 and Miyota 9039 share a case, and what changes if you move between them.
Same footprint, different calendar. The Miyota 9015 and Miyota 9039 share the 26.00 mm x 3.90 mm case fit, but the Miyota 9015 is centre seconds, date at 3 and the Miyota 9039 is centre seconds, no date, so a swap needs a dial cut for the new layout.
The Miyota 9015 is the slim premium Japanese automatic, a lower-cost slim alternative to the 2892 platform. The Miyota 9039 is the no-date member of the 90 series, popular in clean-dial microbrand watches.
They differ in calendar layout (centre seconds, date at 3 vs centre seconds, no date). 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.