Seiko 7548-700X "Quartz Diver" was in production approximately from 1978 to 1985, a run of approximately 7 years, carrying the 7548 quartz caliber in a 42 mm case rated to 150 meters.
The quartz sibling that shared the era with the Turtle and handed its slim case forward to the 7002.
Dates carry a "c." because that is what honesty requires: Seiko's own archive gives only approximate production windows by caliber, so the file states the documented range and marks it as such rather than inventing precision.
The full collector's file for this reference — variants, dial codes, and the authentication walk-through — is on the writing schedule; the specifications above are the permanent record.
Vintage Seiko divers are the most frankenwatched category in the affordable vintage market. Aftermarket dials, bezel inserts, hands and crowns outnumber originals in the wild, and correct-looking watches are routinely assembled from parts. Before bidding on any reference in this family: ask for caseback and movement photos, check that the serial's production window matches the dial code, and price a full service into every purchase.
Production windows and specifications compiled from documented collector references and period catalogs, cross-checked across independent sources; manufacturer records for this era are approximate by Seiko's own account.