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.
Look under your vehicle and count them.
Look under the vehicle and count them.
Should be able to remove the inspection cover and look at it.
Take a look at the left (drivers side) valve cover. It should be near the rear and the top. There is a short rubber hose attached.
It has a breather instead of a valve It is located at the back of the engine and is a block mounted to the engine. It does not look like a traditional PCV. It is deep on the engine block and very difficult to get to.
If you look through the grill on the front of the truck you will see it. It looks just like the radiator and it is bolted to the front of the radiator. It is about the same size as the radiator.
Look for the port(s) on the ac lines. they work like a tire valve. Should be a round blue thing.
what dose a 1999 Alero transmission look like.
If it was built after the 6 month of 99 then it will work. but if it was built in the early month of 99 then NO. look at the sticker on the door jam and you will see that info.
on top of your valve cover on the passenger side of pick up should be white and look like an L. It just pulls out there is really no need to replace it you can clean it with WD 40
Look on your valve cover. It should be connected to a hose going to your air breather.
Slide in under the truck behind the drivers door and look up in the frame and you will see it.