I've had my 12 KR 250 SRW for about a year now and love it. It get's way better mileage than my 15 6.2 did, it doesn't even know the toy hauler is hooked up and my wife loves to drive it allowing me to sleep!

The one thing that bugs me is that it sits with the rear just a touch low.

I've thought about putting bags on it, but I don't want to ruin the ride if I have to have air in them all the time. I think the air bags would be great when towing, allowing my leveling hitch to do less work.

What about putting F-350 blocks under the springs. I thought I read that they are about an inch taller.

The other thing having the rear a little higher is to help keep the stupid back up sensors from seeing the ground all of time and screaming at me.

 

I had the same problem. There is a TSB out specifically addressing the issue, and I researched it thoroughly. What you are talking about is replacing the 2" F250 blocks with 4" F350 blocks. The problem is, if you believe the TSB, you will need new U-bolts, new shocks, and even a new drive shaft! The cost for parts is about $2000.00 IIRC.
The route I chose is AirLift Loadlifter Ultimate 5000 air bags. They incorporate a jounce cushion inside the bag so they can be run without air. They are also the only brand I found with a life time warranty on all parts. Most manufacturers only offer that on the hardware with a two year or less warranty on the bags.

 

How was the install?

 

Harder than shocks, easier than headers.
The manufacturer has gone to great lengths to make the install as easy as possible. There is no cutting or welding required, and regular hand tools are all that are really required. The instructions are pretty easy to read and understand with lots of photos and drawings. They claim 1 to 2 hours which seems accurate for someone working under a lift with pneumatic tools, but at my age, it takes that long just to get up and down on the ground!
No need to remove anything, simply using a jack with a tall block under the hitch will lift the body up enough to give clearance for inserting the bags. Doesn't take a lot, just basically unloading the suspension.
Final note - I don't have upfitter switches, so opted not to install a compressor. For my purposes one of those 12 VDC air pumps works just fine, especially since I have a power port under the back seat. I also use that same pump to winterize my travel trailers.

 

I think the TSB is wrong, all you need to do other than swap the blocks is install longer U-bolts. At least that is what everyone on here has done.

 

That may be the best explanation of difficulty level I've ever heard.

I have a bonus gift card burning a hole in my pocket, I think I'm going to order them.

 

Good move, I think air bags are a more flexible solution, too.
I got mine at sdtrucksprings.com a good outfit, very helpful and responsive.

 

Easy. I did mine in around an hour with two 6 ton jackstands and a set of cribs. Jack it up, set it lightly on the stands under the spring hangers. Remove the wheels and u-bolts and take the lower shock bolts loose. Lower the jack until the blocks are loose. Slide in new blocks. Jack it up so the blocks are tight, reinstall all the parts.

Rear jackstand on the rear spring hanger mount, crib under the stand. Your u-bolts will be upside down compared to how mine were:

 

I did air bags and it made the ride better than stock. I dont have the bump stops anymore but i run about 15# when not towing and 65# when I hook up the 5th wheel.
It sure made the truck ride better when unloaded

 

I have the airlift ultimate a also and love them. I keep 10 lbs empty and 40 with my TT hooked up. No noticeable difference empty but tons better when loaded.

 

Ordered! I'll install them next weekend.

 

Good deal!
Time now for tips and tricks:
1. Soak the mounting nuts on the jounce pads with PB Blaster to help with removal. My first one started spinning as I removed the nut, so I put a pipe wrench on it. That worked great, which meant the second one had to come up with something different. The bolt started spinning inside, so I ended up cutting it off. Wasted a lot of time futzing with two items that should have taken ten minutes or so.
2. A lift is awesome if you have one available. If not, it's quite a bit harder to reach both sides of the frame. A helper can come in handy, if only to hold a wrench on the outside while you tighten on the inside.
3. Metric ratcheting box wrenches are very handy.
4. Remove the spare tire. Even though the spare tier heat shield is still in the way.
5. For some reason the passenger side airbag assembly slid down between the tire and the frame quite easily. I did the driver's side first and did it like the videos, so I don't know if it would have gone in from the top or not.
6. All the nyloc nuts are 9/16" plus two 3/4" nuts and bolts.
7. I installed a "tee" in the airline so both bags will always have the exact same pressure and I only have to fill through one valve. If you carry heavy off center loads, independent valves for each bag will give you more load balancing control.

Good luck! Holler if you have any questions!

 

Thanks for the tips! I like the "T" idea. I'll go back and check that out.

 

SON OF A &*@#!!! Install is going along smoothly, getting ready to put the bags into the truck and realize I only have one clamp bar. WTF!!!!

"thank you for calling. our office hours are 8 -5 mon - Fri..."

 

Yup, happens to me all the time. need something, look at the watch, hmm, 5 minutes after the parts/tool/whatever place has closed.