OK, I am late catching up on this.
Eddie used a first generation Eventide on Fair Warning...it is all over the record. The Eventide came out in the 1970s, people.
Here is a little tidbit from a translated issue of Japan's Young Guitar:
"'82-'83 Diver Down tour when he was beginning to use rack equpment.
Not much info on the tour equipment used for the third and fourth album tours, but in a '84 Young Guitar magazine interview EVH stated that for the Fair Warning recording sessions, he used an Eventide Harmonizer. A large change in his rig happened on the 5th Diver Down recording and tour, when he began using the modded Marshall mentioned on page 17 (at this point he apparently began to use the Variac to lower the AC voltage to around 90V), and it also seems to be the time he started using racks. Also changes were seen in some of his main effects, with new additions being an MXR Analog Delay, a Roland Chorus/Echo (unknown if an RE-301 or RE-501 but used mainly for the chorus). Also an AMS echo for recordings, and for touring, a Lexicon PCM-70 (for the delay on "Cathedral"), an Eventide Harmonizer (a 949 or H-3000), a Roland Digital Delay SDE-3000, a Rocktron Exciter/Hush II, and a Rane SM-26 rack mount mixer."
Take a look at this link for a quick overview of when Eventide Clockworcks introduced their various harmonizers:
http://www.digidesign.com/products/details.cfm?product_id=3680
I have read in several interviews with Ed that he used a Strat for all of "Push Comes To Shove"...I believe it is also stated that way in Van Halen 101. I can check it later tonight and confirm......
You can clearly hear the harmonizer, it is all over the record...wherever you hear a "thickening" of the tone, but you don't hear a swirling time based effect...that is the harmonizer. Look, when I first heard that he used it I was mystified as well...then I went back and actually listened, and you can hear it plain as day....listen to "Dirty Movies" when he really gets his slide cooking..that is harmonizer.
ALSO, since we are talking pickups and getting an authentic Eddie tone...have any of you ever heard Phillip Easterling, who goes by Strat78 on the Guitars101 and EddieVanHalen.com? His clips, using a PODXT with an MXR 6 band pushing it up front and a combination of vintage Ibanez Destroyers and homemade Ash bodied strats, are amazing. His playing and tone are the closest I have ever heard from a home recorder..and his knowledge of Eddie gear and recording techniques is amazing. One of the keys to the early album tone is a the Ibanez SUPER 70 pickup in a Destroyer.
Mike