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In the world of engineering theory, a shaft with a universal joint at each end works best if the angle at each end is identical. The reason is simple. If the angles are not equal. the effective length of the shaft changes as it rotates. In a driveshaft, that means the trans yoke moves in and out on the output shaft of the trans every time it rotates. I looked at the Ford shop manual, and for reasons Ford must know and I do not understand, they have an entire array of pinion and tranny angles for various models and none of them are equal. In my years at the drag strip, we set 'em up so the angles were equal. If your trans angle is zero, I'd prefer to see the differential angle as close to zero as possible. Ford, however, has different specs. The pinion angle changes a lot as you go over bumps, load the bed or tow the boat. More importantly, it changes the most on hard acceleration, when the pinion nose climbs in response to the traction of the tires. Whem that happens, the springs go "S" shaped and the suspension loads and unloads as the pinion nose goes up and down like a perverted frog. We commonly call that wheel hop, but it is really the whole suspension system hopping. That's where traction bars come into play. On acceleration, the front of the bar hits the front of the spring perch and limits the "wind up" of the differential. They also plant the tires harder by lifting the front of the chassis. That is the good part. The bad part is that by creating a rigid arm from the axle to the frame, the axle is limited in its ability to absorb bumps by going through the normal suspension travel. Hence, the ride is worse. A final note and important note: Traction bars should have a U bolt that goes over the spring so that they do not rotate downward on braking. Don't leave the U bolt off to save weight. I did on a Super Stock C car and when I kicked the tranny into neutral at the end of the pass, it went into reverse. The bars came down and hit the track, pole vaulting the rear of the car about 6 feet up in the air. The car was in the air long enough that by the time it came down, the tires were rotating at about 120 mph in reverse. With 8 pounds of air in the slicks, it was not a fun ride. Yeeeehaaa!!!!!!