So, an update on these.
When I tried to submit for a refund on the defective shock, Rock Auto’s website said I could not return them because they are not supposed to fit on my vehicle (2018 Yukon XL). So, I tried to submit a return for the 2nd shock, this time saying that I installed it on a non-XL 2018 Yukon, and then the website allowed me to return it. So, I was sketchy on if they would actually refund my money when they got it back. I included a printed email from Arnott saying that they were a factory replacement for my vehicle. And, they did end up refunding my money.
When I submitted for a refund on the one faulty shock, they would not send a replacement, only issue a refund as an option. So, I ordered a 3rd MR3840. Having already done the two before, the third swapped in pretty quickly. And, after installing this new shock, my “service suspension” dash alert went away.
The truck rode a lot better when having the faulty shock in, when compared to the old, blown-out shocks. And, getting this replacement shock in and getting the suspension system activated improved the ride by quite a lot. Very noticeable, especially in corners, as others have said.
Then I got the rears replaced, and man does this thing ride like a dream again. I watched a couple youtube videos about replacing the rears and neither of them took off the wheel well covers. I would recommend taking them off. It is a handful of easy screws and makes the top bolt of the rear shocks much easier to access. And, I could work on it from a stool, rather than having to lay down on the ground and reach up the whole time. Easier on the shoulders, imo..
Anyway, I would recommend these Arnott MR3840s. A little pricier, but a good option for DIYers that want the OEM, magnetic ride quality without having to pay the dealership and arm and a leg.
