Chris, the bottom line is whether the wheels are parallel to the keel (neither toe in nor toe out). Various things could make the struts of unequal length, even when the wheels are lined up properly.
Try putting a long straight edge (4-6 feet) against the rim of the wheel, parallel to the ground and touching the rim or side face of tire at two places (one ahead of the stub axle and one behind). Measure the distance between the front end of the straightedge and the keel, and then the back end of the straightedge and the keel. Adjust the drag struts as needed until the front and back distances equal each other. They don't have to be equal from one wheel to the other as long as each wheel's plane of rotation is parallel to the keel.
Make sure there is an adequate amount of thread engagement between the barrel of each rod end and its stud. If you must screw them out until only a few threads are left engaged, make a new, longer drag strut tube.
On Dominators, this "toe" adjustment is performed with a welding torch, blacksmith style.