Not so N.O.S after all. Just came across this looking for the previously mentioned post and thought it was another one. Turns out it is a clone.
Flattop.

Very interesting Flattop. Here is another variation. Single hole so the banjo bolt should have a bleeder on it. I think this was a Japan made piece that was on ebay. Which on of you guys has this on the shelf? Lou

You might know where this one went (is) Lou. Parts swapping? And, what frame is that? Not an NCR. MikeV

GPM Mike, been wanting and waiting for years! Lou

GPM had their own version of the NCR spider clutch. Probably as rare as any of the exotic non-OEM clutches. This aftermarket offering looks very well done. Do those banjo bolt/ bleeder screw combos' actually work?
Flattop

I asked myself the same question when i saw this for sale a while back. One way in - one way out. Not the same as a caliper or master cylinder. But they work on the clutch L/H slave cylinder. We need an expert. MikeV

I have used one in many different application they work,never had any problems bleeding with one.

Paul