Just for 'whatever':
Your '83 Shadow has round gear dogs with the option to mate with almost twice as many 'round'ish' female slots on their opposing mating gear surfaces as later years of Honda Shadows. Later years of Honda Shadows have squared off, flat surfaced, curved oblong, shaped gear dogs. The increased (and fewer available hook-up points) friction of the squared off surfaces slamming into the female slots produces a pronounced 'clunk'.
It is not anymore complicated than that.
Honda switched over to the later Shadow engagement dog design because so many 'Johnny speed shifters' were wreacking havoc on the rounded cogs of engagement.
