A quick search show they aren't available anymore either. 1st question is are yours really shot? NLA means you have to make choices on re useing things you might not if parts were available.
I bought some LASO branded rings for mine, and I plan to use them in my damaged trans, where I know the ones in there are beyond re use, I drained most of them out on the 1st oil change.
If you really need only one, I could send you ONE, more than that, you'd have to wait until I have my trans apart and know what I need.
You'd have to have been very hard on the trans to need a full set. Mine was destroyed by The PO and a dragging clutch. I have driven it with essentially no syncro in 1st and 2nd for more than a decade.
Don't forget, when the pinion bearings fail the gearsets move around in the trans, which can negate the syncro's ability to prevent clash. Open and look before deciding they are shot.