Yes there is...
Get the car up on jackstands and level it the best you can. Drop a plumb bob down off one of the front lower control arm mounting bolts on each side and put a mark on the floor. Go to the rear and do the same off the bolt that holds the front of the leaf spring to the frame. Measure the distance between the marks front to rear and diagonally. If you mark carefully, that will tell you if the front sub-frame is square to the rear suspension. The measurements should be within a 1/4" I would hope.