All ’76 to ’89 FMJ spindles will work, as well as all R-body and ’75-79 B-body spindles.
I hadn’t seen a new spindle for sale, in decades.
There are tons of good used spindles out there.
I had to replace one on my wagon about 18 months ago, because wheel bearing failed damaging the spindle beyond reuse. I found one at a local pull-a-part for about $15 (US)
BudW