JK DANA 44 rear differential SHIMS question

[drevo1]

Recently became the owner of JK 2015 Sahara.
I noticed that with the rear axle hanging, the wheels rotate very hard, and there are also extraneous sounds, as if the bearings had become square.
I dismantled the rear axle, removed the differential, the differential was clamped, the gears rotated very hard.
Took apart the differential.
And I saw that the shims between the diff body and the gears of the axle shafts have a conical shape.
In all the photos of the repair kits for dana diff, these gears shims look flat
Does anyone know exactly what they should be?
(small shims, which are also conical under the satellites, but the photo shows that they are conical from the factory)

 

[drevo1]

We don't have repair kits in stock and need to wait up to 4 weeks.
Therefore, I heated the shims with a gas burner and leveled with a hammer, they became flat.
The thickness of the two shims together was 4.5mm with a conical shape, and when aligned the thickness became 3mm. I put everything back together and the differential began to work smoothly, quieter, effortlessly, though there is a backlash of the axle gear of the order of 1mm, probably these are the consequences of working in a clamped state.
I collected it, filled in new fluid 75w140, started the car on the lift, there were no extraneous sounds from the differential. (the old gluid had a lot of fine metal dust, like silver paint)

I have doubts if I did the right thing.
And I'm scratching my head about how these shims could become conical shape if they come from the factory flat. (both axle gear shims was conical identically, it was possible to put one into the other very tightly)