Depending on what Arnott strut assy the dealer put in, there are a couple that fit;
SK-4261 has a 1" white spacer underneath the coil spring. That spacer lifted my '17 Yukon XL 2WD a Full 1" from it's original ride height. It was actually an 1 1/4" rise depending on how you looked at the tape measure.
MR-3840 has a 3/32" spacer underneath the coil spring, this brought the ride height back to factory specs/looks.
After speaking to Arnott on several occasions they determined the correct P/N for my Yukon XL. They said that in the developmental stage of the Magneride Strut, they used a 2WD Suburban as their Test Bed. After many different versions of that strut, they were satisfied with the MR-3840 and released that to the public as the Factory replacement.
They said soon after its release they started getting feedback saying that the MR-3840 dropped the front end on the people with 4WD SUV's, they also had received reports of people requesting a slightly higher version for their needs/wants as well. So they added the spacer and made the SK-4261 the standard P/N for ALL Yukon XL's 2015-2020.
It wasn't until I called them (from what I was told by Arnott) and told them that my XL had been lifted, that they told me the story of their test bed and the 4WD communities feedback. My particular taste is lowered, not lifted and I had considered taking that white spacer out and contacting Arnott for that 3/32" spacer. But Arnott wasn't having that!
They shipped two (2) MR-3840 to me for free, and included Return Shipping labels. They asked that when I removed the SK struts and installed the MR struts that I stick those old ones in the box and ship them back to Arnott without me spending a dime!! Other than the gas to drive over to FedEx to drop them off!
As I said in another Post on the Forums, it took me all of about an hour to swap out both sides. I stopped to light up a Macanudo and open up a Modelo during this time and would have probably finished the job much sooner if I hadn't!
Marvin, Robert & Vanessa from Arnott were the ones who hooked me up, couldn't be happier with all three of them!
Go to the Arnott website and plug in those P/N's and see the spacers I am referring too.
Cheers!
Chad