I disagree; the 04 Pistons were a lot deeper than the 05 Pistons that took the Spurs to 7 games, and the 04 Spurs didn't have Barry. Their backup PG situation was a mess with Jason Hart also, and Nesterovic was their center (they didn't get the Rose for Mohammed gift from Isiah until the next season). Duncan was healthier in 04, but I'm not sure that cancels everything else out. I think the 04 Pistons would have probably won the series in 6 against the 04 Spurs.
For instance, their shallow bench in 05 was a huge problem in game 7 when Duncan got the Wallaces and McDyess in foul trouble in the third quarter, and they got stuck putting Prince on him (of course Duncan went off). In 04 they had not only the Wallaces, but Mehmet Okur, Elden Campbell, and Corliss Williamson to throw on Duncan. I think they were much better equipped for guarding Duncan that year,