80-84 FLT, 81-84 FLTC, 82-84 FXR, 82-84 FXRS, 83-84 FXRT, 84 FXRSDG
For precision belt adjustment, kits for aluminum-primary Big Twins include a BDL idler that makes sure belt tension is correct (tin primary models use tranny adjustment for correct belt tension). All kits use 31-tooth engine pulleys and 47-tooth clutch pulleys.