Remington Nylon 66 bolt action
There is no Nylon 66 bolt action rifle.
There's a semi-auto Nylon 66 .22 is that what you meant?
The Remington Nylon .22 rifles that used nylon stocks were pretty standard .22 Remington rifles that used the same sights as the wood stocked versions.
If you need a Nylon 66 semi auto sight, rear sights are very difficult to find. The sight was riveted to the "receiver" cover. Both sights and receivers with the sight are rarely seen.
You might contact Jack First and ask:
Gun Parts is out, and while I doubt they have any, you might contact Remington and ask.