The problem here is this is a Coronado neck code and this may tempt many builders to try to pass a Coronado neck as a Jazzmaster.The key info here is a Jazzmaster neck with this code will have a full sized large CBS headstock.Slowly this number become the standard code by 1967.To add more confusion, I have also seen stock mid-late 1966 Jazzmasters with "10" codes.If it looks like a Coronado headstock or like an older smaller Jazzmaster headstock, then the neck is not a Jazzmaster neck. Earliest F tuner equipped guitars feature Kluson tuner hole piloted necks with factory filled screw pilot holes.There are also a small number of Jazzmasters with factory equipped Grover tuners.These tuners have a square pearloid button and a hand engraved F on the rear cap of the housing.
The later version features an R in a circle after Fender.
The pickups changed in this era in that the factory began winding them with a winding wire known as Bondable Polyurethane winding wire that is potted using a denatured alcohol solution. The alcohol doesnt penetrate the coil so these pickups tend to be a little microphonic.
Most guitars found with this system of labeling have February 1966 stamps. There appear to have been Olympic white guitars made with the black CBS logo, and some metallic finishes have the older over the finish decal.
The new CBS logo was then briefly discontinued from standard use and does not reappear until the type A decal is completely phased out in 1967.
Factory insiders claim this era the pickup magnet material was changed to a more cost conscious formula.
The pickups from this era tend to sound a little different from earlier pickups, often described as sounding darker. Then the code changes to a Stratocaster code of "13" by the start of January 1966. The "13" code lasts well into 1966 and the code "19" becomes the 'official' code during the year.