All I know is from people who have had them rebuilt only to find out they had vibrations after the so called rebuild.
And or the old FD was not rebuildable after it was cut open.
I think so called rebuilds are somewhere around a $1000.00?
They cannot simply be rebuilt like a torque converter....noting to rebuild ..just a front bearing, graphite ring and very specialized high quality machine surfacing work for the graphite ring seal surfaces, maybe a new bellows if they can even find or have one.
Then the re-welding the unit back together so it is as accurate and balanced as factory new... that's where the rebuild failures seem to happen from what I've seen and heard.