text news wrote:

The engine in our 1972 C172 (0-320-E2D) is now due for overhaul.....
If we get a Lycoming exchange engine how do we know
that it hasn't already been re-worked two or three times and would be
rejected at the next overhaul?

Why do you think this is important? This engine lasted 32 years. Do you really
think that you will still own the plane 32 years from now when it needs another
engine?

Even if you do still own it, this will only matter if you do a field overhaul
next time. If you swap for another Lycoming rebuilt, you'll get a different set
of parts (collectively known as an engine) and it won't matter if your old ones
meet the serviceability limits or not.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.