lined them up alongside the old ones as a reference for initial install length.
Measured the distances between the outside edges of my tires to make sure it wasn't grossly off.
Good enough to get to alignment shop.
my .02$
My intentions were to set them up at the same length as the stocker however they were grossly bent. Just eye balled it and used a string to dial it in initially. If possible, pay for the lifetime alignment option. Any time you make adjustments, you can take it in and have it re-spec'd.