rebuilt 4kq rear calipers sticky/seizing - recomendations?

[Dave C.]

Re: the rebuilt calipers I bought, I meant to add...

When I received them I was surprised to find they were BARE metal ... no
cad plating, etc, so they immediately rusted and now look pretty bad.

I didn't expect this or would have allowed time for painting them, but
under the circumstances needed to install them right away.  I don't know if
 this is standard practice for rebuilts to be shipped in this condition,
but I don't  think they should be installed that way.  I think the rusting
would contribute to early failure of the seals.
Dave C.