Are you referring to the Mercedez 10mm billet spacers? Did it fit on your SRT without modification?
https://www.ezaccessory.com/. Is the site I got my 10mm hub centric spacers that I tested today, nice snug fit and you order the lug bolts you need. For the 10mm I would get 50 or 55mm. The 55 will go all the way through the hub with about 3mm sticking out. Hub centric is a must!
dan