Study this photo carefully
This course builds upon the foundational knowledge of the floating 400-series bridge that you acquired during your undergraduate studies.
Let’s begin our discussion by examining a unique topic: the different placement of the floating bridge over the years (please note the placement of the bridge relative to the 3 screws mounting the base plate to the body). Who would like to volunteer to explain to the class what we’re looking at here? During what years was the 'short' placement used vs. the 'long' placement, and when did the placement change? Bonus points: which placement was used on the reissues, and was it the correct placement based on the model designation?
From @ronsvintageguitars:
What we're looking at here are the base plates of a (1969) model 420 on top and a (1964) model 450 on the bottom. The "short" placement of the base plate prevailed through 1965; the 'long' placement is seen starting in 1966. The base plates on the 425 and 450 V63 reissues of these models were not correct for those models. Since they were reissues of the Geo Harrison 1962 model 425/450, they should have had short base plates; instead, they had the post-1965 long baseplates.