Balancer assembly's requiring just one bearing (two of these will NOT work in a twin row balancer)
2001; Suitable For All Models; 400, 470, 501, 550, 650
2002; Suitable For some models in; All the 400 Models, and early 2002 470, 501 and 550 models. All 650s are twin row
2003; Suitable For The 400 Model Only