Only one of the Carli 2.5" systems (Leveling System) does not include rear shocks nor any form of rear lift. They offer that as an entry level setup for the front that you can add on to in the future. All of the other 2.5" kits from the Starter Kit up to the King 2.5" Pintop kits include rear shocks and mini packs. The only guys that would need new blocks are the F350 customers as they would need to replace them with F250 blocks. Customers with F250's wouldn't need anything extra.
And you are correct that the King 2.5's with Carli's proprietary piston and valving can't be beat.
We're confusing with our blocks because there are SO many different combos one could run. With the leveling kit (no rear included) F250 customers need to run the f350 block as the 2.5" of front lift is 1" more than needed to level an f250 as they're normally only rakes 1.5". The addition of the f350 block puts the rear right where it needs to be.
As stated above, the f250 block will need to be used by f350 owners if the add-a-pack will be utilized with the any or the leveling systems. If an f350 owner wants just the leveling kit, then no rear block is needed and rear shocks can be added to the leveling kit for $170.00.
Skyd Ram I wasn't sure if purchasing 2 king piggybacks and 2 king shocks (rear) with Carli leveling springs, track bar, brake bracket, and cam bolts,would be cheaper? I am new to the power stroke suspension game but don't see why new leaf packs would be necessary?
They are add-a-packs, not to be confused with full progressive leaf springs. The add-a-packs maintains one's ability to haul up to factory payload without sacrificing load capacity while smoothing out the ride of the factory springs by means of removing the factory upper and lower overloads in favor of installing a progressively engaging "mid-pack" to support the springs.
Why do we do this? All of our systems are made to be functional and increase ride quality. The stock leafs are a HUGE hindrance on the ride of the truck; thus we figured out a way to maintain stock support and only use as much spring rate as necessary for a given load resulting in a substantially better ride.
Next; are they needed? No, nothing about any aftermarket suspension is needed. People come to us as they need the capability of a 3/4-1 ton truck but hate the ride. This is a problem we're in the business of correcting and we put together kits to accomplish this task. As for constraints, we can put a kit together to accomplish anything you're out to accomplish (subtract rear add-a-packs, do a leveling kit with Kings and no rear, etc...); however, these are tweaked on a case by case basis. Hope this helps!