14 bolt swap question

[Polloso]

I know this has been covered a thousand times however before I purchase this rear end assembly I would like to make sure my scheme will work. I have an 89 K1500 RCSB with a stock 8.5" 10 bolt. I found a 9.5" 14 bolt SF rear end but with the 8 lug axles from an 88-98 3/4 IIRC. I should be able to put 6 lug axles in and probably have to change the drum brake backing plates. Does this sound right or do I need to find a unit that came with the 6 lug axles. Thanks fellas

 

[JOHNGAAA1]

It will be a little work hunting, there are 14 bolt rears with 6 lug axles. Why go through the trouble. I have one in mine. 1998 k1500 z71 gmc sierra. They do exist. You need to make sure the ratio is the same in the front and the back.

 

[Polloso]

Yeah I have 4.10 in the front and rear. The one I found is a 3.73. I also have another spare 8.25 front diff with a 3.73. As far as the rear assembly I found it seems to me from what I've read is to get 6 lug 33 spline axles. The only thing I'm hung up on is the 6 lug axles are like 32.5" and the 8 lug are something like 31". I would think the difference would be with the drums somehow

 

[ShadowRejects]

I bought a 14 bolt 9.5 semi float from a 87 Suburban squarebody. Had to reweld the shock tabs and spring perches, so you're already one step closer than I am.Mine was 8 lug. Wish I would've kept it being I went 8 lug about 2 years later and had to run adapters, which I still have with zero issues.
When I converted it to 6 lug, I swapped to 6 lug 10 Factory axle shafts, and tossed on a Lugnut4x4 disk brake conversion kit. If you plan on keeping the keeping the truck, I'd consider looking into it. It's relatively cheap. The Eldorado calipers are a pain in the butt, but there are many reputable kits out there that utilize different types of e-brake disk brake conversions. Many of which are direct bolt on

 

[Polloso]

Yeah the rear disc's are cool but I'll stay with the 11" duo servo drums that come on the larger rear ends as they are pretty good. Maybe disc's down the road if I keep it. Right now I just wanna make sure a rear end with 8 lug axles can have 6 lug axles swapped in without any issues with the factory 16" wheels or brake issues.

 

[Supercharged111]

If the axles are a different length, then maybe the housings are all the same? This came up very recently in another thread and I want to say someone claimed the housings are the same, but don't quote me. If so, don't forget backing plates. I have no idea where to find those new. Also, did you find a 2wd or 4wd? Those are different for sure.

 

[Polloso]

I think the housings are all the same and it's the axles that are different lengths but that is what I'm going to be gambling on. Not sure if it's a 2 or 4wd. I think as long as the spring perches are 47" center to center all is good as far as it bolting up and the axles will make up the width difference. I have a 67.5" width on wheel mounting surface to WMS. If the 6 lug axles are the same width in the larger rear end then its just the brakes that are the variable hence the different backing plates. We will see. Wanted to check here first before taking the plunge!

 

[Schurkey]

Are you looking at a C2500 axle, or a K2500 axle? Far as I know, the C and K axles are different widths. Which maybe explains the axle-shaft length problem.

I'm prepared to learn something...but...I have NO idea how the rear wheel track widths can be different, the axle shaft lengths can be different, and the axle housings be the same width. Look at where the bearings ride on the axle shaft--if the axle tube isn't longer for the longer axle shafts, the bearing wouldn't be in the right location.

Right?

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Aside from the 6-lug axle shafts, you'd also need 6-lug brake drums. I don't know why the backing plates would be different. By the time you buy new axle shafts, and new brake drums...maybe it'd be better to just get the 6-lug axle assembly to begin with. Kinda depends on the condition of the axle assembly--are the axle shafts or drums worn-out? If so, you need to buy those parts anyway.

When it was me, I got a "K2500" 6-lug axle for my K1500 6-lug truck. Bolts right in. No wheel hassles, no brake drum or axle-shaft hassles. Needed four U-bolts, the U-bolt plates from the donor vehicle to match the axle, and a conversion U-joint (#441, I think) for the rear of the driveshaft.

In my case, I also needed to swap shoes around on the rear brakes because the previous owner of the axle did his own "brake job" when he was clearly unqualified.