4 spring Triumph or later model BSA clutch - Installation of this clutch is a significant improvement over the 6 spring BSA clutch. These later pre-unit clutches are identical between BSA and Triumph except there is BSA mainshaft piece. As a side note, the A10 and Gold Star clutch [4 spring] are the same as Triumph's but the hub adapter for the BSA can be different [depending on which hub adapter] by 3/16" in alignment with the engine sprocket and you may have to shim the engine sprocket out 3/16". In addition, the clutch shaft in the transmission for the A10 is longer that the main shaft in the GS. [explains why the engine mounting plates on the A10 are off set.] That would cause a huge alignment problem for either bike - is using the wrong transmission and also explains the different length clutch rods. Also, the splined bushing in the cush drive [the part that splines onto the crankshaft] has several different width shoulders between the engine sproket and the bearing spacer that goes on just before the cush drive. This also changes alignment. There are several different spacers listed that can be inserted into this space to help provide alignment. The spacer that goes between the inner primary and the engine case is not listed in earlier parts books, the later parts books do show it. It should be used in all cases. Without the spacer, the oil seal grooves on the inside of the clutch bearly engage the alloy slider in the inner primary case.