Yup, drill the crossmember to the same dimension as the OD of the spacer.... Before you weld it in place you'll have to have the upper A-Arm in position so that you can get the caster/camber correct on the install...... I've got a number of pics in my gallery showing various MII installs... But, the caster and camber have to be withing range of the available adjustments before anything is welded in place permanently.....Did you get the crossmember with the lower arms, or is it the existing one in the car???