Transmission shaft angle question

On my 69 Dart I have been redoing the suspension after breaking a spring perch and have a question.
The car has a Tremec 5 speed. After measuring the angles I have; 5 degrees down on the rear axle, 5 degrees down on the transmission, and a 5 degree angle on the drive shaft.
So the rear angles are good, my question come from, after reading the Mopar Chassis book.
It says that the transmission angle should be 2.5 degrees or less. There is no way to raise the tail shaft up that far to get that angle. The manual says that 1/8" changes the angle 1/4 degrees.
Who has measured their tail shaft angle and what are you seeing?