Part number 43050-5002 is the correct part number for rear pads for the 1977 KZ650-C1. If the Z1E pads are equivalent to that part number, as the ad claims, they will work. The pads on the stock 1977 KZ650-C1 rear brake are shaped like the ones in the Z1E picture; they are not rectangular. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)