Any idea where I can find a spindle for my 1970 plymouth duster

It would appear that some FABO members are confused as to what you actually want. Well maybe just one, lol.
But,
Have you already taken the caliper off to verify that it is NOT the guilty culprit? The reason I ask is cuz in 50 years I have never seen a seized spindle-bearing, whereas I have seen lotsa seized calipers.
LOL re your comment about confused members. As to the caliper - yes, caliper is off. Rotor and bearing are seized on spindle.