They can be sanded and polished, on the exterior, to look, if not new, then pretty darned close to it.
P500
P800
P1500
Trizact 3000
(All wetsanded)
Polish
I made a sticky on cleaning the interior of the housings.
https://www.crossfireforum.org/forum...-assembly.html
And it IS amazing how much grunge will build up on the inside of the housings.