Where are the oxygen sensors on a 1999 GMC Suburban?
Depends on the year. Here is a site that has pictures of an EGR valve for a 1997 - 1999 Suburban: http://www.racepages.com/products/?D=gmc+suburban+egr+valve&Nty=1&Ntx=mode+matchallpartial&Ntk=Main&N=4294950670+4294963366+9926&Dx=mode+matchallpartial&Ntt=gmc+suburban+egr+valve Go to www.racepages.com and search for an EGR valve for your year rig.
If you are referring to the SBC 350 L31. 1996-2003 Chevy Express/GMC Savana full-size vans 1996-1999 Chevrolet/GMC C/K full-size trucks 1996-1999 Chevrolet Suburban/GMC Suburban full-size long-wheelbase SUVs 1996-1999 Chevrolet Tahoe/GMC Yukon (and 2000 Tahoe Limited) full-size short-wheelbase SUVs 1999-2000 Cadillac Escalade