These are the absolute best shocks you can put on your Titan for around $100 each....period! We sell a ton of these because they work and ride well. These shocks are sold as just the shock(no spring or upper mounts..if you have a Daystar leveling kit, you may want to buy new upper mounts from the dealer) A good spring compressor makes the job a snap. if using the acme-thread type, please use 3 instead of 2 legs, as it will make the job way easier. Sometimes the stock shock stud bolt will be seized to the shaft and cutting the nut off the end of the stock shock with a saw is easiest...this is rare but important for you or your installer to know. 
These shocks offer 3 height settings...0-1-2inches of lift. On the 08+ 4wd titans we dont suggest more than the fist notch of 1", you can set it taller but the ride starts to degrade in our opinion. On any other titan, you can run them at any of the settings. Most Titans will look just a tad nose-down with these shocks installed...not quite a true level. On the 08+ 4wd, at 1" of lift the truck will look the same as the other versions on 2" lift....got it? good.
These shocks are slightly longer than stock. Bilstein made them as long as possible without any coilbucket contact, we dont suggest adding spacers, ANY SPACERS, to these unless you have aftermarket upper a-arms and then it gets pretty specific what thickness spacers can be run as well as cam bolts, endlinks, and taller bumpstops. All that being said, using these shocks as they were intended requires nothing else be added.
Lots of interweb yapping about combining these shocks with the 08+ 4wd/pro4x springs....DONT! just a bunch of bad info. The reason people do that is that before the 5100 were available, we would combine the longer (but still same spring rate) 08+springs on the HD/4600 series bilstiens to get lift on the earlier trucks...alas, these shocks do what those springs did...adding the longer springs will just decrease the amount of adjustment you can get. Adding the springs or a spacer will not get you any more height unless you run the proper upper a-arms and associated hardware. If it were just that easy, we'd have offered a kit like that a long time ago. 
Yes, these can be used with most 4-6" bracket lift kits...BUT, you will get coilbucket contact as these are longer than stock and, with enough abuse, the shock body can collapse if jumped. Many, many people have great results with these (a great combo w/ the RC 4" bracket lift) but a handful have learned the hard way and bilstien will not warantee them if used with a spacer or on a bracket lift.
There has been some install issues concerning the proper placement of the washers included with these shocks, the new instructions cover this. Simply, you will reuse the factory upper washer and the new bilstein washer goes "inside" the spring. it may not make a lot of sense here, but you will realize during installation. IF the new washer is used to replace the old washer, the shocks will install just fine but after a week or so the shock shaft will push through the bushing assembly resulting in no shock damping and a bunch of noise. The shock is still 100% fine but the spring will have to come off and a new washer installed...not the end of the world but a pain in the ass none the less.
We sell these as a pair for $219 shipped in the 48 states. We will also answer any questions you may have on these if you bought them trough PRG. If you decided that they were a dollar cheaper somewhere else, and are having issues, please call somewhere else for assistance. These generally drop ship from a Bilstein Warehouse.