More info on the differences for the B line; 1976 KZ750B1000001 - KZ750B2016100, first model; 1977 KZ750B2016101 - KZ750B2025700 only changes were a lockout switch for the starter; 1978 KZ750B3025701 - KZ750B3033000, Dynamo and regulator changed position of front caliper changes and they used needle bearings in the swing arm; 1979 KZ750B403301 - til the end, logo and color changed.