suspension replacement

Sorry if this has been answered else where. I have looked for an answer to no avail. I have an 05 GT Limited and one of my rear shocks is leaking so I am looking to upgrade. Would like to keep the stock springs for now but looking to upgrade struts to the Bilstein HD. Will they work with stock springs/ ride height or would I have to match them with a set of lowering springs. Also if they do work what is the part number for rear struts for my car since no website I look at seems to have any listed as compatible? And from my understanding for them to work I will need all new Spec B top hats, correct? Thanks for the help and sorry if it was posted elsewhere but all I saw about the Bilstein was in relation to the OB XT.