I would venture an educated guess that ALL rebuild kits come filled with Chinese -made parts, including the ones that Sun Valley has used forever.
That being said, I bought two complete kits over the years from Precision International, and had good luck - the replaced clutch plates, seals, etc; lasted about as long as the originals.
I got a good idea of what OE parts would really cost when I had to replace two tiny little plastic check valves in the valve body, and they cost more from the dealer than the entire rebuild kit from Precision.