On mine, it seems that it's also the stub axles. On the rear, the bearings fit very tightly on the stub axles and in the hub. In fact, I had to heat the hub using a hair dryer (I'm using the aluminum hub) and then the bearing went in easily. I thought about freezing the stub axle, but I was able to get it in with moderate pressure. The front hubs went together more easily, but again, the bearings were smooth until the stub axles were installed in the bearings (that were already installed the hubs). I did not have to heat the hubs in the front to get the bearings in.

I didn't have to drill out the hub carriers at all. The issue appears to be the steering block bushings. Also the steering blocks do not fit snugly in the caster blocks. On one side, after I installed the bushings, there was some slight drag. I was able to fix the drag by installing a small shim between the bushing and the bushing bolt. On the other side, even with the bolt snugged down, the steering hub is a little loose in the caster block. I tried installing a shim between the steering hub and caster block, but I couldn't get everything lined up correctly to get the bushing to seat in the steering hub. I tried the kit hubs, and I had the same issue (I'm using the AE FT aluminum steering block). I also tried sanding down the upper bushing on the side with the excess play, and that seemed to make a difference, but I left it for now until I can figure something else out.

It's too bad they can't make the steering blocks as smooth as the steering rack.

Also, anyone know why AE changed the design of the rack? The new design uses longer tie rods. I assume they did it to change the bump steer characteristics.