nice story! love those buicks. did it have the 401 and dynaflow?
i found some info 64-65 used a 25 spline that snapped so they went with a 28 spline in 66. my case is 24" so it must be a fairlane,galaxy,or a murador due to the offset of the shifter for bigger body style, my best guess.
Thanks for all the help!!!!!!