Replacing rear axle on 83 k5

My k5 has a 10 bolt rear

The truck has a 454 6” lift and rides on 35s

I’ll looking for stiffer gears …Probally 4:10s

One seal is leaking and can’t get the axel out because there is a broken screw the lag guy left me with.

SO I’m thinking about finding an upgrade. 14 bolt already with the gears I want. What year donors can I drop in? Are there any 14 bolts that have 6 lug hubs?

Appreciate any advice

What broken bolt are you taking about?

I don’t know going by what mechanic told me. I trust the shop for both honesty and knowledge. He told me they went to remove a bolt so they could remove the axle but it was already broken off.

Said it could be drilled out but if I was looking for gears anyway it might be better to get a new axle

BryanS said:

I don’t know going by what mechanic told me. I trust the shop for both honesty and knowledge. He told me they went to remove a bolt so they could remove the axle but it was already broken off.

Said it could be drilled out but if I was looking for gears anyway it might be better to get a new axle

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Okay it's the bolt in the diff that holds the cross pin,they always break if you don't heat them with propane before trying to remove them. They are an easy cheap fix,so common some one makes a kit with the proper drill bit,drill guide new bolt etc. I'll see if I can find it for you. You do know with a K series if you change rear gear ratio,you have to change front gear ratio? You will not be able to drive 1 inch in 4 wheel drive until you do so. Fixing your diff is the most affordable plan. I'll see if I can find the kit. I'm assuming 8.5 inch 10 bolt. Read this link.
Not what I'd use but that's because I have what I need and am confident on my abilities,but for someone who lacks the confidence,here you go.
Also,why they break,they use loctite new,you need to heat them.

Thank you

Guy mentioned that there might be a kit to get the old bolt out.

I understand needing same ratio front and back…was kind of thinking if I got an Axle in rear with stiffer gears I would then get the same gears for front axle

So do I get the bolt out, buy (2) gear set or do I buy used axle for rear and buy one gear set for the front

I'd fix what I had and buy 2 gear sets,but I do my own work. Talk to your shop about both options and price out a used rearend vs. a gear set.

Ricko1966 said:

I'd fix what I had and buy 2 gear sets,but I do my own work. Talk to your shop about both options and price out a used rearend vs. a gear set.

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What do you think about the 10 bolt behind the 454 and 35s? rather not put money into it if I will end up blowing it up in a few months anyway?

I’m really not interested in getting 8 lug wheels so staying with the 10 ( or 12?) would help me there?

A 14 bolt semi floater (9.5") from a K1500 "heavy half" gmt400 pickup is a 6 lug axle. A little wider than a square body axle (it makes the front and rear track widths the same), but will require new spring perches and shock mounts.


This one I built is now under my friends 75 K5.

^ same axle that I got to go under my truck.

Are all gmt half ton “heavy”

What about the gmt 400 suburbans are they donors too!

BryanS said:

Are all gmt half ton “heavy”

What about the gmt 400 suburbans are they donors too!

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I found on another forum the f44 package had semi float 14B with 6 lug. If this is the one I want how do I find which donor truck has that option?

BryanS said:

One seal is leaking and can’t get the axel out

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Well the good news is, you qualified for the Axle Hall of Shame Award.

BryanS said:

What do you think about the 10 bolt behind the 454 and 35s? rather not put money into it if I will end up blowing it up in a few months anyway?

I’m really not interested in getting 8 lug wheels so staying with the 10 ( or 12?) would help me there?

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Your overall question is lacking enough info to answer.
Just because it’s a 454 doesn’t mean it has the power to be snappin axles. And even if it does, are you using it in a manner to be snappin axles?
What transmission? If it’s an original 700r4, it will be the weak link.
If it’s a built 700 then disregard (maybe).
Since the 454 is not original (I don’t think they made factory big block 80s blazers) does it have a non OD or OD trans? If OD and you want to drive freeway speeds at low rpms then deeper gears makes sense. If non OD, 4.10s will be screamin on the highway even with 35s. 4:10/35” tires 1:1 = 3000rpms at 70mph +/-

Grit dog said:

Your overall question is lacking enough info to answer.
Just because it’s a 454 doesn’t mean it has the power to be snappin axles. And even if it does, are you using it in a manner to be snappin axles?
What transmission? If it’s an original 700r4, it will be the weak link.
If it’s a built 700 then disregard (maybe).
Since the 454 is not original (I don’t think they made factory big block 80s blazers) does it have a non OD or OD trans? If OD and you want to drive freeway speeds at low rpms then deeper gears makes sense. If non OD, 4.10s will be screamin on the highway even with 35s. 4:10/35” tires 1:1 = 3000rpms at 70mph +/-

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Thanks Grit
This truck is new to me and I’m suspect of the guy who had it before me. Some things he did great somethings are cheap and stupid

I really don’t know what the motor’s got in to it. It’s got a bit of a cam, rpm manifold, old micky Thompson valve covers and a brand new 600 CFM Holley. Don’t know if someone had a plan or just threw whatever parts together.

stomping on the gas I’ll spin the back tires a little w/o power breaking. Whatever that means for the HP/torqe

I don’t think it’s going to be snapping axles unless I go out of my way to do it…yet. By the time I’m done I’ll be looking to get some serious power out of it.

I’m in FL and there are no rocks to crawl on, plenty of mud to mess up my pretty paint job and a ton of shopping centers to get groceries from.

It is a 700r4 with OD … .70 I think so is that 3000 x .7 = 2100?

I understand this may well be the weak link and i was planning on dealing with that when/if I get there

I’m looking to make this truck bad a** so I’m trying to be smart and if I will need a bigger rear eventually I would rather not put money into the 10 bolt.

It’s not my daily so highway speeds are not overly important but I would like to be able to rip tree stumps out of the ground and pop wheelies if I line up next to someone at a light

^Well it sounds like it’s got decent power. My otherwise stock gen vi 454 converted to carb “should” be around 300hp….I think. It would posi squeal the old crusty 35s pretty easy. Not so much with new tires now.
But from what you said, your overall plan seems to support a heavier duty axle for those mud runs and extreme curbs at the Dunkin’ Donuts drive thru.
I don’t speak from experience but in the same position I think I’d lean towards a newer 6lug 14 bolt in 4.10 and redo the mounts. Probably a wash $ wise having someone do that vs re-gearing and you get a much stronger axle. I believe semi float 14 bolts are pretty durable. Bonus if you find one from a truck that doesn’t have super high miles and has clean gear oil, shouldn’t have issues for a long time.
JMO.
Sounds like a sweet ride!