You are correct in the way you have set the pinion angle in relation to the transmission. The problem is that the ujoint angles at rest are too close to zero. So angling the pinion down 3.7 degrees puts the ujoint angles at odds with each other at cruising speed, but then under full throttle , the pinion will rise and swing the rear joint past zero degrees into the proper angle.
I would raise the rear of the transmission and lower the pinion, or lower the trans and raise the pinion, whichever is more practical.
This video helps explain it.
http://youtu.be/Idk3BVDVHq4Good luck. Joel
