I actually tore apart my Nitro Burner and Radio Shack Road Phantom (surprisingly different chassis) recently, and ya, I really got my response wrong... First off, for the Road Phantom, most of the bearings are 1150, the only ones that aren't are the ones coming out of the housings, which on the later years, use an odd 14x10 bearing and it also has a shoulder on it, which means you'd have to find a flanged bearing too, so that would be hard, I just left the nylon. On an older Dictator I have, there's a reducer that allows a 1150 to fit instead of the 14x10. I don't really know what the wheel bearing are on the newer models now that you mention it. I'll have to check that.

Also, the gears are actually MOD 1, so that was a pleasant surprise. And it turns out my gear failure was inside the spur gear, which doubles as the diff housing - the carrier supports inside the housing stripped, the actual spur teeth were fine. One last surprise was that the counter gear was internally spring dampened, shocking - hobby grade they say...

I'm going to scan, mesh, and model both RCs because I'm finding the 30 year old exterior plastic easily breaks, so unless yo have a 3D printer, be gentle, the housings will snap...

I don't think anything got cheapened between Nikko vs Radio Shack branded RCs. I have a few of both, over multiple generations, and of the different size varieties - changes seem consistent among both, if one did it, so did the other. The cups used to be more stout early on, so you probably saw that version, which is more popular in the aftermarket/hobby world, but these aren't much of a failure point regardless. You'll notice inconsistency among parts because of this, just changes over the years, but, for the most part, the major parts are compatible/interchangeable within the same size chassis, I think...