its according what kinda front suspenion you use,,, parrell springs . or transberse spring,, the parrell springs will match the withe of the axle spring perchs, that will match the the frame although you can mount the springs on the out side of the frame,, transverse springe set up , you radious arms will need clearance, they will ride on the outside of the frame, so it need to be narrow enuff to allow that,, it just depends on the front end and the look you are going for,, oh , what i am talking about is for a straight axle not ifs!