I went with the complete strut unit, the savings for swapping out the cartridge didnt seem worth the work, plus the springs have lot of mileage on them, sure they prob work ok, but new was quicker and easy install, I say easy after having to remove entire rear interior to access bolts, on the front having to remove the plastic cover under windshield wipers. After removing everything it takes to access the struts I was glad not to have to do the work it would have taken to replace cartridge itself. I was able to find complete set of 4 for less than $300, not sure how much garage would charge to remove what it takes to access rear struts but probably cost more than what entire strut set cost, plus there is a certain amount of danger separating the springs from cartridge, but wasnt worth the time for me