I know this is a rare occurrence (HA!) but my  rear quarter panels are
leaking rust along the crease. My local body repair people suggest that it
can be repaired but it would be even better to replace and have identified
the following parts that they would need and have asked me to see if I can
find them.

Wheel House: Right #251 809 156 Left # 251 809 155
Lower Corner  Right #251 813 356 Left # 251 813 357

I'm a neophyte at this, and it's the 1st time that's the most confusing.
Any suggestions on sourcing, if they even exist new as replacement parts,
etc? If there are multiple sources, is quality the same, as I assume it
would not be OEM, etc?

Thanks,
Art