The wire was grounded via a staple on the face of the guitar below the tailpiece mounting plate.The tub design first changed with the rhythm controls section in 1962.I should also mention the rare Grover tuners available in the late 60's.
Dating vintage kluson tuners
Earliest models have 'tubbed' style shields in both controls routes.
These have a bit of brass that lines the walls of the cavity as well as the walls.
Sure enough all the factory original examples had the veneer.
Early-mid 1966 Jazzmaster can be found with three different decals.
The later version features an R in a circle after Fender.