Drop-in resolution
ETA 2893-2 vs Sellita SW240-1: do they swap?
Whether the ETA 2893-2 and Sellita SW240-1 share a case, and what changes if you move between them.
Close in diameter, not a drop-in. The ETA 2893-2 (25.60 mm x 4.10 mm) and Sellita SW240-1 (25.60 mm x 4.60 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 ETA 2893-2 is the GMT member of the 2892 family, base for many caller-GMT travel watches. The Sellita SW240-1 is a Sellita automatic with small seconds at 6, in dress and field watches with a sub-dial.
They differ in height (4.10 mm vs 4.60 mm), calendar layout (centre seconds, GMT 24h hand, date at 3 vs small seconds at 6, date at 3). A 2892-A2 with an added 24-hour hand for a second time zone at 25.60 mm x 4.10 mm. The extra GMT train and hand mean it needs a GMT dial and hand set; its drop-in donor is the Sellita SW330-1.
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.