Stamper said:

Can anyone preserve Dirty Harry original mixes? Mono and stereo. It's on this collection of LDs. The remix is horrible. http://www.lddb.com/search.php?search=dirty+harry&sort=title

I don't think any of them were originally stereo, except for The Dead Pool.

Look at the back of this LD, and there's a tiny "reprocessed for stereo" credit.

http://www.ebay.com/itm/Dirty-Harry-The-Enforcer-Clint-Eastwood-Laserdisc-LASER-DISC-Warner-Brothers-/221225534976?pt=US_Laserdisc&hash=item338211c600

Early pan and scan releases might be the best source for the mono, at least for the first film.