Arizona has no infantry units, no cav, no armor, nada, zip, nil. The only combat arms in the state are two artillery batallions.
The closest you can get to being a grunt is to go artillery as a 13F, aka FISTer, aka a forward observer. 1/180 FA is direct support to the 11th ACR and has a shit load of FO slots, most of which are filled by ex Army or Marine infantry types. 1/180 is currently activated and home deployed for Noble Eagle. 2/180 has their warning order and is deploying to Iraq (as MPs) around January.
There are two MP companies, the 855 which just got back from Iraq (with 20 Purple Hearts) and the 860th which is just now being formed from scratch and is Iraq bound in the next few months.
There is also an Engineer Company. The 258th (??) I don't think they are really high speed sapper type engineers though.
The Marine Reserve only has bulk fuelers. The Air Guard has the 161st Security Forces Squadron. They don't train much for shit, but they have lots of SHORT deployments available all over the world.
The USAF Reserve has a Para Rescue detachment in Tucson, if you are a truly high speed motherfucker.
The good news for a wannabe (or usedtobe) grunt is that 1/180 is scheduled to transition to infantry very soon. This is also the unit that has a lot of 13F slots, so its probably your best bet. The FOs drill in Mesa on Center Street.
You can IM me if you have any other questions. If you're going to join I could use the referral credit so shoot me an IM or Email before you do.