Probably an '86 (136= 13 week of 6th year of a decade) build then of a 1963 design...'87 being the end of the line. You got the upgraded '74 version large frame 1.8hp 2:1 reduction 360-400-440 starter there as opposed to the small frame '63 version 1.5HP 3.75:1 slant and teen starter.
