BHD

Depends on which lift you ordered. I run the factory block on my Crew and deleted it on the RamCharger and my '90 W250. Its best to run with out it, decreases axle wrap and torque on the u-bolts. If you have to keep it, it shouldn't be an issue for your ride.

J10Mike

What he said. If you go with a lift system, which includes new rear lift springs, you wont need the rear blocks. That will make your rear ubolts too long.
Look at that pic. Imagine no block there. Ubolts too long and no thread to tighten nuts..

oliver foster

On my '85 crew cab that I bought 6 inch Skyjacker front and rear springs for 10+ years ago, I needed to reuse the factory 3 inch block. With the recent Dana 80 swap I could loose the block as the axle tube is thicker and I need to use a 1 inch Zero rate spring to move the rear axle back 1 1/2 inches. I needed to move it back for driveshaft room, as the Dana 60 to Dana 80 "pigs head" is longer.
I also welded a 3/4 in mounting plate to my Dana 80 axle perch to get the right center bolt hole size. Between the 3/4 mounting plate, 1 inch Zero Rate and the bigger Dana 80 axle tube, my ride height stayed the same.

I would bolt the rear axle all together with the old U-bolts and the factory blocks and see if you like the ride height.
Modify it, if necessary, until you like it then use fresh U-bolts for the final assembly.

Azzie

Good info Oliver. I did some research and skyjacker says to use stock rear blocks with their DR40S springs which is what I'm running in a 4 inch. I was wondering today if I could trim them down if it had to much rake as the CTD is coming up soon. I thought if it is to tall in the rear I'd like to lower it some. I don't want any cali look just want it to sit level. Glad there is some room to customize.

J10Mike

You can also find blocks in various heights should the factory block be too tall.

Azzie

Mike it's funny you say that cuz I am currently looking up some now. This has become an addictive project 💰😜

J10Mike

Tell me about it. Every time I think I'm finished, I think up a new project...LOL.
It's never ending.

Azzie

That's right. I was trying to sell some motorcycle parts today to buy the cross over steering and twin stick from ORD. Figured while I'm in there. Never ending is right. Found a Super Duty rear seat that is cherry and have a 400 mile trip ahead of me Saturday. 50$, I couldn't pass it up. Lol.

oliver foster

The Factory blocks for Cummins 1st gens are 3 or 6 inch.
ORD makes that Zero rate spring, which is a 1 inch block that bolts to your leaf spring pack. It allows axle movement front or back 1/2 an inch OR 1 1/2 inch along with just keeping it in the stock location. I keep a few of them on the shelf for suspension fine tuning.

Azzie

Just looked these up and I think I'll have to get a set. Kinda two birds with one stone. When lifting a truck is it common for the axle to move forward/rearward? Being the need to center the axles?

u2slow

Not usually, but a shackle flip can. I found it favourable to un-center the axles for other reasons. 1/2" fwd in the front to help steering and driveshaft fit. ~1" aft in the rear to avoid shortening a driveshaft. Can't tell looking at the truck.

I got ORD's D60 5/8" thick ubolt plates at the same time. I see now they carry a thinner axle offset plate:
Axle Offset Plates for 4x4 Suspensions from Offroad Design

Azzie

It's probably not a bad idea to have some plates in the tool box just in case some fine tuning is in order. Waiting on one last u-bolt for passenger front and we will be slinging wrenches. Thanks for all the input as this is only the beginning. Hopefully life slows down a touch so I can start enjoying it. Thanks all

oliver foster

I used them on my white crew cab after my Dana 60 - Dana 80 swap to move the axle back 1 1/2 inch as my other option was to cut down the driveshaft.
I also wanted as little block height in the back as I could have and still keep it looking right. When I removed the 3 inch block I needed the 1 inch zero-rate to maintain the perfect height as well.

I could see using them if needed on the front axle if tire clearance was needed, or as U2slow used them.

Azzie

I'm worried about the stock blocks on the rear. They seem tall and I don't want a bunch of flex. I order some zero rate to address drive shaft issues if they come up. Looks like Tuesday night I'll start this project and see where it leads me. I'm thinking it is going to lift it 6 inches beings it saggin -2. Lol. Be like a new truck with new shocks, springs, cab bushings.

BHD

I'm running OE blocks out of a '93 W250 on my Crew. They are about 6" tall. There is a little wrap but not too bad. If it gets worse, I'll install traction bars.

I also run a stock lift block on my '77 W200 that I truck pull with, the 440 is pretty hot, and it wraps the back axle hard with no issues for the last 5 years.

I recommend trying your set up with the blocks, it may not be too bad.