4321887 bearings are used in the Excavator Final drive system of Hitachi ：
4321887 BRG.;ROL. Hitachi parts CHR70, EX100-2, EX100-3, EX100-3C, EX100-5, EX100-5 JPN, EX100M-5, EX120-2, EX120-3, EX120-3C, EX120-5, EX120-5 JPN, EX120-5HG, EX120-5LV JPN, EX120-5X, EX120-5Z, EX120K-2, EX120K-3, EX120SS-5, EX130H
