Changing rear ends but also driveshafts?

Before you spend any cash on a drive shaft you have to do the following:

Build the rear end and set it in the car with the springs your are planning to run and the weight on all 4 - wheels.

The yokes on the output shaft of the tranny and rear end, make them take the same size u-joint for balance issues.

Measure the shaft that fits YOUR car, there are production tolerences and the shaft in mine ended up 3/8" longer than the factory recommended shaft length with new springs.