The 5-7 degrees is indeed how much the front axle needs to be leaned back. However this is controlled by whatever you attach the spring too. I always thought that angle was built into the crossmember . and if that is the case that angle is pre set assuming your frame etc will be at stock configeration . In order to check or set the angle , your frame and or crossmember needs to be at your final ride height and angle ( the angle your frame will be at ) which is determined by the size of your tires -big and littles cause a front down rake- your suspension , a 4" dropped axle brings the frame down 2-4" from stock , the weight of your engine and accesories .OR you can ignore all this ,build the car and when you are all done check the angle of the axle and place a beveled shim between your axle top and the crossmember until you get it right . This way is much easier and unless you are lucky doing it the other way you will probably have to shim it any way . If you are going to run with fenders , the crossmember needs to be in its stock location so the wheels fit under the fenders where they are supposed too.