Here they are on e-bay right now.
http://www.ebay.com/itm/YAMAHA-WARRIOR-350-CARBURETOR-YFM-350-YFM350-1987-2004-ATV-QUAD-BRAND-NEW-CARB-/191126057797?pt=Motors_ATV_Parts_Accessories&hash=item2c80003345&vxp=mtr#ht_4275wt_908
And yes they are plug_and_play, just install them and you are good to...