This 4842 is a very solidly made quartz - your watchmaker will love it! It was made in 1975, early on in the production run of the 48 base caliber, which spanned just four years.
In the first year of its production in 1975, only this Grand Quartz reigned supreme right next to the Quartz V.F.A with just three models, 8000/8010/8020, there were no other GQ calibers! The models 8030/8040 were introduced later in 1975 and made for just three years; they came with a thick steel band for the 4843 and with leather only for the 4840 & 4842. That setup never changed for this caliber. Even when the much daintier 48xx-8110 variation was introduced in 1977, ending the 8030/8040 production run in that year.
In 1978 Seiko introduced the twin quartz 9943, ending all of the 48xx caliber that year. This 48xx of the years before however remained a thicker and wider flaring watch (38x41x12mm!) and was more robust than its 9943 descendant - it is after all a Tanaka design. Therefore it already has a huge presence, apart from its very modern dimensions.
This 48xx-8040 has a definite "butch" personality to it as evidenced by its measurements of course... It is the definite early king of the 48s, as other variations like the 8110 are already smaller with lugs of 18mm instead of 19mm and dimensions of 36x40x10mm. For that matter, this 8040 already has the smaller case size compared to the 8041, even if it is only one millimeter less from lug to lug (41, not 42mm). Also the lugs have a slightly different shape to them as seen from the front - which makes them seems shorter. Apart from that pecadillo however, this watch is thoroughly understood and functioning perfectly. It is not the twin brother of the 4843-8041, but definitely a very similar sibling.
Describing this watch reminds one of the unparalleled quality of these early Seiko Quartzes. For instance, the thermo-compensation, due to its relative thickness, is still excellent after all these years. The Silver linen dial work of course is impeccable, truly a high end watch. You noticed the black striped hands? It gives this watch something extra..... great legibility and some "punch". And that punch is also implemented in the mechanics of this watch, it has that special Seiko gimmick of the "jumping seconds hand". This means that it will jump ahead 10 seconds when you pull the crown to adjust the time. It makes time setting so much easier!
The Grand Quartz at hand is fully original and runs to specs.
In my experience these single quartzes are among the most accurate vintages; the twin quartzes like the 99 series mentioned have the specs for sure, but after 40 years or so… build quality and robustness gain the upper hand. The early Grand Quartzes truly shine!