The body shape remained unchanged with two exceptions. The 90's reissues had the same shape but were thinner (top to bottom) and the GSR shape was significantly different in dimensions and proportions. Because of the changes in the headstock and tuners the bass has to be matched to the case. For example a '67 will fit in a 70's case and a Newark Street case but the Newark Street will not fit in the 70's case.
SF II's did not come with thumb and/or finger rests. Thus any SF II that has them was either a conversion from a SF I or a post-factory modification.
The earliest basses had the rests evenly spaced between the sweet spot pickup and the neck ("original"). They remained in the same location after the pickup moved to the neck position and then finally migrated to an offset location. All three configurations occurred during the Early era (an approximately in that chronology). The offset position occurred in the Vintage and 70's era. The original configuration is also observed in the GSR and Newark Street eras.
The earliest of the Early era saw three different pickups, commonly called the "Mickey Mouse", the "other Hagstrom" and the Hagstrom "Bisonic". There is no clear data indicating which pickups were used when. The Bisonic was used at the latter part of the Early era and in the Vintage era. A Guild humbucker was used in the 70's. The 90's reissue had a pickup that was similar in cosmetic appearance to the Guild humbucker and it is most likely to have been made by Duncan to specs based on the 70's pickups. The GSR pickups are cosmetically like the Guild humbuckers and it has been stated that they are original "vintage" pickups, presumably the 70's version. The Newark Street has a new pickup designed to recreate the Bisonic both cosmetically and sonically.
One way to distinguish between the '70's and '90's humbuckers is to remove the pickup and look at the back. The pole pieces protrude from the back plate in the '90's pickups but not the '70's.
There have been
Two pickup basses (SF II) were produced in all eras. One pickup basses (SF I) were produced in all eras except the 90's reissues.
SF IIs all had the pickups in the same locations, almost flush against the neck and just above the bridge.
SF Is had the pickup in one of two locations. A location by the bridge (the "sweet spot") was used in the Early, GSR and Newark Street eras. A location by the neck was used in the Early, Vintage and '70's eras. The "sweet spot" location in the Early era predates the neck location.
The neck location was the same on a SF I and II but the "sweet spot" is slightly closer to the neck than the bridge position of a SF II.
There is an emerging hypothesis that some SF IIs started out as a sweet spot SF I and had a neck PU added. If it is true then it is worthy of its own post.