My Ford alternators in my Cessnas have lasted more than 600hrs. My
buddies with Mopar alternators in their Pipers aren't so lucky...

I'm currently flying a Piper with 900 hours on the alternator and it's
still working fine.

BTW, the Piper service manual contains the procedure for replacing the
bearings, brushes and diodes inside the Chrysler alternator, so an A&P
can legally perform a field overhaul on them.