Dhotrod---- Nope, a 40 Ford spring won't work in a model A frame. A model A spring sat directly above the rear axle tubes, while a 40 spring was offset from the top of the axle and attached to the end of the radius rods. The only way I know of to achieve a 3" or 3 1/2" drop is to remove the leaf spring and fabricate a set of coil over shock mounts which attach to the banjo rearend and to the original rear crossmember.---then of course you would have to add a Panhard rod as well.