These cup joints are for use with assembly type universal shafts for more efficient and smoother power. Compatible Chassis: TT-02*1, TT-02D*1, TT-02B*2, TT-01 Type-E*1, TT-01 Type-ES*1 & TT-01D Type-E*1 Chassis 1Use with Item 53671 and Item 53792 pairing. 2 Item 53671 and Item 53791 pairing.