From 73-76 most CB750K parts were bolt-on swappable. 77 CB750K models were a larger design departure from the earlier models and some parts became swappable as long as other parts were bundled into the swap, such as ears and signals, or fenders and fork lowers. Some items although swappable would change the bike's handling characteristics, such as forks, shocks and swingarms. Some parts, although they would bolt on, I would not consider them swappable, such as gauges, seats, fenders and signals, as these required some fabrication to make then align or work properly. The newer swingarm allowed fit of wider wheels and tyre yet would still bolt-on (I believe it was a tad longer also, but I could be wrong).
