Hi Ian,
I’ve actually never understood what exactly is behind vintage mk1 or mk2. I’ve never seen any of these designations either stamped or inked on the bottom of a Pu-plate.
So let’ be precise now:
1) I’ve had or have ’78 and ’79 LS-50/60 reborns and I found absolutely no markings on Pu’s. But I simply would call them paf copies – same construction, similar measurements, each with a slug and a screw coil, brassplates and ceramic magnets, read both about 7.5k and have 50mm polepiece distance (from outer pp centers). Sound depends on the guitar, neck perfect, bridge often too bright or harsh.
2) Since around ’80 (my source are two LS-80 reborns) there’s an inked stamp “Patent Applied For – made by goto” version. A different construction, only screw coils, polepiece distance is more matched to string distance (47.5mm for neck - 50.5mm for bridge), Pu-cover screw-mounted, not soldered, reading 7.5 to 8.0k. These Pu’s are louder but not hotter than 1) and sound very good.
I found the same kind on ‘82 and ’84 LS-50 Loverocks, which were much louder again, caused by thicker screwpoles and two instead of one leading rail, but neck is sometimes too loud compared to bridge.
3) All of my ’81 LS-50 Loverocks are stocked with Pu’s “GOTOH” impressed on the brassplates’ bottom. Construction is comparable to 1) but hotter (8.0 – 8.5k) and louder (taller screwpoles). I assume that these Pu’s followed 1) for LS-50/60 models in 1980. Since “reborn old” were only built for a few months in 1980 I don’t think that there’s any difference concerning the Pu’s compared with reborns or earliest loverocks.
4) A closer paf replica is the “Tokai ’57 P.A.F. MODEL” (sticker) version, nickel bottom plate, alnico magnets, paf-like construction, reads about 8.5k, more creamy, starting around ‘81 in LS-80 models.
5) Those mentioned in 2) obviously developed during the 90’s till 2000 into much hotter (around 10 to 11k) versions which are supposed to be still in use. The newer ones have small Gotoh stickers and F/R markings for front and rear positions.
The models from LS-100 upward were basically equipped with dimarzios (pafs or super distortions), or seymours (SH-1 or SH-55)
Feel free to correct or add any information