AFTERMARKET TORSION KEYS- yes you can use them without messing up your truck, by fallowing the same rule above, don't go past 24 1/4 inches. Which can be attained with the stock keys, which is why everyone will tell you there worthless. Aftermarket keys are great to get you back to that height if you have a heavy aftermarket bumper or a snow plow in the winter.

1997-2003 Lift Options:

Torsion Bar Cranking:
Preferred method of raising the front of the truck on the cheap, a better option than buying keys; keys are not recommended.
*4wd only
http://www.fordtruckclub.net/forum/s...ead.php?t=1786

Leveling Kit: For 2wd trucks a leveling kit will consist of spacers to place on top of the coil spring to give the truck an extra couple of inches.

Spindle Lift Kit: Another 2wd only option, these will typically raise the front 3"-4", allowing you to fit a 33" tire with ease. This is a very straightforward lift option, the stock spindles are simply replaced with new ones. Fabtech is one of the quality options for this lift http://www.fabtechmotorsports.com/pr...lay=FORD%202WD

Blocks:
Common method to raise the rear, fairly straight-forward yet they should be used with caution. NEVER stack two blocks on top of one another, this is extremely dangerous and should be avoided. The stock blocks on these trucks come with bump-stops, when you replace the stock block you will no longer have bump stops. This can lead to bottoming out your rear suspension and could lead to damage at the rear of the truck. I would personally recommend getting some aftermarket bump stops that sit on top of the leaf or buying blocks with the bump stop built in.
It is worth noting that wheel hop can be increased with larger blocks.

Lift Shackles: These are actually shorter shackles that replace the stock shackles to allow the leaf spring to sit lower on the frame, raising the truck. Lift's from shackles are in the 1" to 2" range and are a fairly cheap option for raising your truck.

Body lift:
These can be found in the 1", 2", and 3" range. Body lifts lift the body off of the frame. The suspension of the truck remains in tact, giving you all the ride characteristics of a stock truck. A body lift kit is typically in the $200-$300 range and provides a cheap way to fit bigger tires on your truck.
Note that you will be lefts with gaps between the body and the frame, this can be covered up with gap guards purchased from the body lift manufacturer home fabricated if you're handy.

Add-A-Leaf: This lift option is for the rear leaf springs on the truck. An extra leaf is inserted into the spring pack, raising the truck a couple of inches. Due to the nature of this lift your rear springs will stiffen, resulting in a stiffer ride. This is a very good option for those of you that tow or haul frequently.

Suspension lift kits:
2"-3" lift kits:
These kits are typically comprised of torsion bar keys, possibly a rear block, and sometimes shocks. These are offered from many different manufacturers ranging from $99 to $300. However most people are probably better off cranking their torsion bars and buying a rear block instead of purchasing a kit.

4.5"-5" lift kits:
These are typically in the $1000 range and provide a fair amount of lift at a reasonable price. They typically include front and rear drop crossmembers, torsion bar brackets, knuckles, and blocks for the rear; new leaf springs or add-a-leaves for the rear may also be an option. This will be a much more involved install than any of the aforementioned lift methods for the front of the truck. Rough Country makes a good kit in this range.

6" lift kit:
Zone Offroad kit https://www.f150forum.com/f6/zone-off...install-64030/
Fabtech http://www.fabtechmotorsports.com/pr...lay=FORD%204WD
Skyjacker http://skyjacker.com/
These kits come in different variations and different price ranges. Some kits may widen track with and component build quality may vary.

7.5" lift kit: This kit will allow for clearance of 35" tires on a 2wd pickup. These kits include new springs, spindles, drop brackets, and blocks or leaves for the rear. Once again Fabtech makes a quality kit in this range http://www.fabtechmotorsports.com/pr...lay=FORD%202WD

Long Travel: Long travel kits are typically found on prerunner trucks and allow for a lift as well as greatly increased travel for rough terrain. Long travel kits are more expensive than a typical lift kit but it is the only option for a true prerunner. There are a couple companies that have long travel kits for these trucks on the market right now
http://www.dixonbrosracing.com/content/view/13/3/
http://www.dirt-tech.com/tp_front_su...8_03_f150.html
http://www.filthymotorsports.com/Cam...am-ltravel.htm

For more lift a suspension lift and body lift can be used together as some members here have demonstrated. Also torsion bars can sometimes be cranked in addition to a lift kit to provide a couple more inches of lift.

After any type of front end suspension adjustment it is always a good idea to get the truck aligned afterwards. failing to do so could lead to uneven tire wear and premature wear in front end components.