maybe I mis-understood. if you are replacing, that means your taking the old one out and putting a new one in, right?
why nut just get the old one of by whatever means necessary, take another car (assuming you have access to another vehicle) and take the lower shock bolt (regardless if you shear it off or not) along with you to the store and get the proper nut and replacement bolt if you hacked off the old one...
I presume I understand properly now...
(I forgot the rears have a bolt and nut, my apology).