Compatibility: Collins Dolly (SLZ). (1 Pc) Left Spindle Assembly with Spindle Shoulder Bolt for Hi-Speed Tow Dolly Collins DFZ-SAL - Steel, Zinc Plated. (1 Pc) Right Spindle Assembly with Spindle Shoulder Bolt for Hi-Speed Tow Dolly Collins DFZ-SAR - Steel, Zinc Plated.