Drop-in resolution
Seiko VK64 (SII) vs Seiko VD53 (TMI): do they swap?
Whether the Seiko VK64 (SII) and Seiko VD53 (TMI) share a case, and what changes if you move between them.
Different footprints. The Seiko VK64 (SII) is 30.80 mm x 5.10 mm and the Seiko VD53 (TMI) is 29.50 mm x 4.57 mm, so they do not share a case. This is a choice between platforms, not a swap.
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The Seiko VK64 (SII) is the bicompax meca-quartz chronograph, in two-register chronograph mods. The Seiko VD53 (TMI) is a TMI standard quartz chronograph (VD5 series).
They differ in diameter (30.80 mm vs 29.50 mm), height (5.10 mm vs 4.57 mm), calendar layout (meca-quartz bicompax chronograph, two sub-dials, date vs chronograph (seconds, 60 min), 24 hour, date), winding behaviour. A bicompax meca-quartz chronograph at 30.80 mm x 5.10 mm, sharing the VK63 footprint but with two sub-dials instead of three. Its different register layout means a VK63 dial will not fit it.
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.