I have bought a few NOS knuckles/spindles (on eBay), but they seem to be rare.
Post a Want Ad in the Swap Meet (here). I got one NOS knuckle/spindle here (maybe 15 years ago).
If you are willing to buy a used knuckle/spindle (or, you have to buy a used knuckle/spindle), be sure to get an agreement that you get your money back if it is not useable. Many/some are wallowed-out where the bushings seat. Bad ones were quite common even back in the 60s/70s (I've been collecting them since then).
A few members have posted part numbers for (Moog ?) king pin repair sets with over-sized bushings (with/without over-sized king pins). The worn-out knuckle/spindle would have to be machined for these bushings.
I do not know the significance of the difference, there are different part numbers for 1/2 ton steering knuckles/spindles:
1946-1950
1951-1953
1954-1959 (I think 1959)
IPre '68 Dave (I think) and others have posted that the difference can be "overcome".
If someone has the motivation, and the parts, a Tech Tip (with "modern" part numbers) would be very helpful.
