Column name truncation

I've upgraded postgresl from 7.1 to 7.3 and am having an issue with the
following:

7.1 would truncate column names greater than 31 characters to 31.

7.3 does not do this, so that backups previously done via pg_dump in 7.1
don't play nicely with my code accessing 7.3

Is there a way to force 7.3 to truncate at 31 characters too?
Or,
Is there a way to test whether a (truncated) column name is in a table? and
if true, rename the column name to it's full (pre-truncated) name?

Thanks