The fuel filter looks like a small metal canister, similar in proportion to an aluminum soda can, but smaller in size. It is roughly 2" in diameter and about the width of your hand in length. There are threaded fittings on the top and bottom.
The fuel filter is underneath the vehicle, along the inner edge of the passenger side of the vehicle frame, roughly half way in between the gas tank and the engine, which puts it roughly a foot below where the passenger sits. Taking a gander at your existing fuel filter will make shopping for the replacement filter quicker and less error prone.
The fuel filter has the designation FF504 (I am assuming this is some sort of standardized part number, as the parts reference catalog I browsed through listed only this number, rather than several numbers corresponding to respective offerings from third party parts manufacturers). It should be available at your local auto parts store (I picked mine up from AutoZone) for under $10.
You will need a 13/16" wrench and a 5/8" wrench. An old rag or a few shop towels might be a good idea. If you will be working in the dark, you will need a lightsource, perferrably positionable.
Before your remove the old filter, you may wish to find the marking which says "Flow =>" and take note of which way it points. However, if you forget to do so, it shouldn't be that difficult to deduce this information, given the location of the engine and gas tank.
Disconnect the forward fuel line
The filter will be connected in-line with the fuel line. The fittings on either end of the filter will be threaded on the inside, and hexagonal in shape on the outside. That hexagonal shape is slightly less than 13/16". The threaded fittings which secure the fuel line to either end of the filter have hexagonal sections as well, and are 5/8".
The fuel line which spans from engine to fuel filter will be metal except for a roughly foot long section near the filter. We will remove the fitting on this end first. Using your wrenches, secure the 13/16" fuel filter fitting, and loosen the 5/8" fitting on the fuel line by turning it counter-clockwise. As the fitting nears the end of its threads, some gasoline will begin to drip out. Continue loosening the fitting until its threads are clear from the filter, and then slide it back along the fuel line.
Using your rag / shop towels, firmly grab and pull the fuel line out of the filter. It will be a little bit of a tight fit. It is likely that the fuel system will be under a slight amount of pressure, and gasonline will spray out of the opening you are creating. Thus, you want to keep the rag / towels loosely crumped and near the opening to prevent the gasoline from spraying everywhere. Expect at least a cup of gasoline to drain from the fuel line and filter. I recommend you take a short break here and let the gasoline evaporate before continuing.
Remove the filter from the rear fuel line and place the new filter into position
Loosen the rear set of threaded fittings in the same manner used above. The rear half of the fuel line does not end in a flexible section, so you will remove the fuel filter from the fuel line, and not the other way around. Again, more gasoline will spill out, but it won't be under pressure.
Grab your new filter, making sure to take note of the marking which denotes directionality of flow, and slip it onto the rear fuel line. Start the threaded fitting and make it hand tight. Take a short break to allow your second puddle of gasoline to evaporate. The remaining trickle of gasoline in the rear fuel line should begin to saturate the filter while you are breaking.
After the gasoline has evaporated, insert the front fuel line into the new filter, and hand tighten its fitting. Using your 13/16" wrench to secure the filter in place, tighten the fittings using your 5/8" wrench. Be careful not to over do it while tightening the fittings.
Start 'er up!
After taking a third short break to allow any additional gasoline spillage to evaporate, start your Suburban. Be prepared to turn the starter while applying pressure to the gas pedal for at least half a dozen seconds. Remember, we are working from an empty fuel line here.
Take a minute to update your vehicle maintenance log.
Check for leaks the following day.
See you again in 30,000 to 50,000 miles, depending on driving conditions.