The measurement only makes sense in relation to the pinion angle. SUA you want a 2 degree difference.
That will be the offset that is managed by the u- joint. If it is greater than 4 degrees you may get driveline vibes going through 30 mph and may have some deceleration vibes at high speeds 60-70. That was my problem
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.
AF Jeep Club Tail Number 184