PIPESTATUS works for me.

$ uname -s -r
FreeBSD 5.4-RELEASE
$ bash --version
GNU bash, version 2.05b.0(1)-release (i386-portbld-freebsd4.8)
Copyright (C) 2002 Free Software Foundation, Inc.
[download]

man bash extract:

PIPESTATUS

An array variable (see Arrays below) containing a list of exit status values from the processes in the most-recently-executed foreground pipeline (which may contain only a single command).