data recovery question

I tried searching the archives for this, but the search is broken. I looked
by hand for a while, but didn't see an answer...

This is for postgresql-6.5.3 running on Redhat 7.0

I'm trying to recover data from a single table file. I recently rebuilt my
server and found to my dismay that my full backups weren't working. My
differential backups were working though.

There is only one table in the database that I care about, and it was
captured on a differential backup. But none of the other files in directory
were.

I tried naively to create a database and table with the name of my old
database and table, and copy my original table file over top of it, but no
deal.

I can see the data in the file, but the data is stored at the field level
not row level, and piecing it back together would be very difficult.

Does anybody have a clear spec on the format of the table files? I checked
the online docs
http://developer.postgresql.org/docs/postgres/page.html
but I think I'd need more detailed specs to write something to pull data out
at the row level.

Or even better, does anybody know of a better way to pull the data out of
the table file?

Thanks much,

Chris