Factory Size Rear Block

[ukjosh1]

Purchased a 1984 K5 Blazer a couple years ago to rebuild with my son as a possible first vehicle for him when he gets older. It came with what I was told a 6" lift on it. I purchased a 4" lift kit from Sky Jacker to lower the truck a little with the hopes of a little better ride and not so top heavy. I'll be happy to keep it if he doesn't like it haha.

The back axle looks to have a 5-6" block on it. However I was informed by Sky Jacker that the block on the rear axle needed to be the factory size. I'm getting mix result online from searching for the original size of the block. I believe its a 2" that I need but not positive from all the different results. Can anyone give me some more solid guidance on to what size I need to get?

 

[cheavyk10]

There were never any factory blocks on any square body Chevy. GM had different spring hangers between the 2WD's and 4x4's on the rear to compensate for the different heights.
Not sure what Skyjacker was talking about, but Ford's and Dodge's of the same era had blocks on their 4x4's.
The standard 4" Skyjacker kit should come with a 4" rear block.

 

[Wes Harden]

Or 4" lift springs,making a lift block unnecessary

 

[nvrenuf]

There were never any factory blocks on any square body Chevy.

Actually.....

The first couple of years of K30's ('77-'79) had a 2" block in the rear, these early 1 tons still had the 2wd size rear spring hangers so they had small blocks to level them with the front axle.

 

[ukjosh1]

Thanks for the responses. I'll just go ahead and just completely remove the block and add the new leaf springs and shocks and see how that looks.

Hopefully there wont be any need for any blocks at all.

 

[cheavyk10]

Actually.....

The first couple of years of K30's ('77-'79) had a 2" block in the rear, these early 1 tons still had the 2wd size rear spring hangers so they had small blocks to level them with the front axle.

Nice! I completely forgot about that factoid!

 

[Blue85]

I purchased a 4" lift kit from Sky Jacker.

Did your kit come with lift springs? Can't you tell with a tape measure whether or not it will fit? Usually the springs will have a part number painted on, which you could look up for the height/application. If they only included 2 springs then obviously they intend for you to use a block.

I was informed by Sky Jacker that the block on the rear axle needed to be the factory size.

How did you order the kit without complete information? It doesn't sound very good for a lift kit company to be unable to look up your application.

The standard 4" Skyjacker kit should come with a 4" rear block.

Well sometimes, they are taller than advertised height, to make up for old spring sag, like 4.5-5", but yes, it seems obvious that if the new kit came with blocks about 4" tall and only two springs, that's the answer.

 

[Stephen]

Yes to all. Good place to start is just put it on and see what you get for ride height. I suspect it'll sit a little low in the back as K5s often do but you'll have to install to see since it depends on condition of the rear springs.

 

[sweetk30]

Actually.....

The first couple of years of K30's ('77-'79) had a 2" block in the rear, these early 1 tons still had the 2wd size rear spring hangers so they had small blocks to level them with the front axle.

3" tall . I have a set and the truck . . Also have cast in ear for bump stop to hit . And i think its only around 1year at most i have ever seen the blocks in them .

 

[Chickntrk]

My 78 K20 had a set of 3” with a cast on bump stop piece? Maybe because it was a camper special?

 

[sweetk30]

Here you go . Best i can get with all the crap piled around .

 

[tarussell]

3" tall . I have a set and the truck . . Also have cast in ear for bump stop to hit . And i think its only around 1year at most i have ever seen the blocks in them .

I’ve been looking into what years things like this were used and from what all I can tell it was 77 & 78 K-30 only for the 2” or 3” block with the bump stop ears - 79 appears to be ( as far as I’ve seen ) when GM started using the longer K-30 spring hangers.

If those blocks are used on the wider spring spacing of the K-10/20’s then I would think that the bump stop would not hit those ears ( at least not centered up ) due to them being further away/out from the frame.

 

[sweetk30]

I’ve been looking into what years things like this were used and from what all I can tell it was 77 & 78 K-30 only for the 2” or 3” block with the bump stop ears - 79 appears to be ( as far as I’ve seen ) when GM started using the longer K-30 spring hangers.

If those blocks are used on the wider spring spacing of the K-10/20’s then I would think that the bump stop would not hit those ears due to them being further away/out from the frame.

Only seen on our squares in as you said 77-earl to mid 78 .

Also my 77 k30 long bed had th400/203 with a 12" or so drive shaft to carrier bearing then long shaft down to axle for the rear .

 

[tarussell]

Only seen on our squares in as you said 77-earl to mid 78 .

Also my 77 k30 long bed had th400/203 with a 12" or so drive shaft to carrier bearing then long shaft down to axle for the rear .

Those 400/203 combos are really long !

 

[sweetk30]

Its in a better place now . Th400 went to friend who builds them . 203 got split for its range box and a ord 2"up doubler kit put on . So parts of it are living on still .

 

[tarussell]

Its in a better place now . Th400 went to friend who builds them . 203 got split for its range box and a ord 2"up doubler kit put on . So parts of it are living on still .

Always good to put cool parts to good use!
I was given the motor, trans & T-case from a SRW 1979 K-30 crew cab that had a 292, 400/203 & 4.56’s years ago.
My buddy knew I was collecting 292 stuff and I got the 400/203 knowing that ole NVRENUF was building his 465/203/205 setup and wanted to use a 32-spline 203. John kept the super short shaft HD case 400 just in case he ever looses his mind and converts back to a two pedal setup - let us all pray that day never comes.

We’ve given each other and horse traded so many parts over the years that sometimes we call each other up to verify who owns what before we get rid of stuff to anyone else - lots of parts over the past thirty-five plus years !