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

The 10” drum spindles are not reproduced, you have to find a used one.

Best bet is probably to put up a want ad here, make sure you specify what side you need because someone might have 1 and not a pair.
That would be too easy.
"Put up a want ad" "That would be too easy" Offers for spindles in the thread are against site rules. If you are looking for parts, new or used, place a free Parts Wanted ad. Yes, it's that easy.