Drop-in resolution
Donor movement for the Seiko NH70 (TMI NH70A)
Which movement drops into a Seiko NH70 (TMI NH70A) case, and what has to match beyond the footprint.
Drop-in available. The Seiko NH72 (TMI NH72A) shares the Seiko NH70 (TMI NH70A) footprint (27.40 mm x 5.32 mm, full skeleton, no date, no seconds hand) and is the standard donor.
The Seiko NH70 (TMI NH70A) sits in the Seiko NH70 / NH72 skeleton footprint (27.40 mm x 5.32 mm) group. The Seiko NH72 (TMI NH72A) share its casing diameter, height and calendar layout, so a case and dial built for the Seiko NH70 (TMI NH70A) accept them with the correct dial and hands.
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.