To add to Bob's reply:

A four link maintains a constant pinion angle. The axle will not rotate. You really need to have the engine and transmission mounted in the car before setting up the four-link, and the car needs to be sitting like it will ride when finished. There is some adjustment, but you need to get it very close to start with. If you try to mount the rear axle by using some shortcut, you take the chance of having to do it over again.