I’m in the process of something similar. I’m taking my jku with 35s and 3.5 lift to 40s on d60s. I spent months trying to figure out how to do it in stages. I thought about getting the wheels and tires and running them gently on my stock d30/44, but the bolt pattern is different. I thought about getting just the tires and running them on my wheels, but mine are 18s, and there’s a crap selection of 40s for 18s. I’m staying 13.5 because here in PA, the fenders must fully cover the tires. I’m also at the highest lift I can go and still keep my bumpers under 30 inches. It turns out with the Dana ultimate d60s, I still will need to run a 3.5 backspace to have steering clearance. Bottom line is o would have had to buy thousands of dollars worth of parts twice to do it in stages. I just sucked it up and ponied up for the d60s. I’m in the process of getting the wheels, tires, driveshafts, some new metalcloak adjustable control arms, etc. I even ordered a rear bumper and tire carrier, because I have no other way to carry a spare. It will cost me almost as much as the jeep by the time I’m done, but that’s the price of being stupid enough to want to run 40s on a jk.

the D60s look awesome, by the way. They come complete with lockers, bigger brakes, and all the upgraded driveline parts you could want (except the shafts) for under 12 grand.