GMT800 diff swap in a square

[RoryH19]

Hello.

I've been researching axle swaps for my k5. I have a 14bSF from a 4x4 gmt400. It will widen the rear axle to basically the same width as the stock front axle.
I was also thinking of converting to disk at the same time since the drums are shot.

I then thought about using the gmt800 with factory disk brakes. I found a 14bSF from an 05 Escalade with 3.73 gears which I already have.
From what I've read the 4x4 gmt400 axle is the same width as the gmt800.

Has anyone done this swap?

I'm sure the spring perches and shock tabs will need to be changed. Maybe a new prop valve too.

Pros/cons?
Anything else to consider?

 

[yevgenievich]

I put a 14 bolt ff from 02 2500hd in to 85 gmc. Moved the spring perches and mixed brake lines. Shock mounts actually worked with some tweaks as is.

 

[RoryH19]

I put a 14 bolt ff from 02 2500hd in to 85 gmc. Moved the spring perches and mixed brake lines. Shock mounts actually worked with some tweaks as is.

Any special u-joint and did you have to change the prop valve?

 

[yevgenievich]

Any special u-joint and did you have to change the prop valve?

My axle came with 1410 ujoint as it was a ff. Sf likely will have 1350. In my case everything else for brakes was left alone for now. I had to mix brake lines between old and new axle. Has a SF 14 bolt with drum brakes prior. Will likely be changing to hydroboost setup eventually.

 

[RoryH19]

My axle came with 1410 ujoint as it was a ff. Sf likely will have 1350. In my case everything else for brakes was left alone for now. Will likely be changing to hydroboost setup eventually.

I have the conversation u-joint to go from 10 bolt to 14b SF.
Did you need to change any brake lines or did they just connect the suburban as is?
I have a hydroboost from an 85 diesel k5 that will be going in too.

 

[yevgenievich]

I would guess a shorter driveshaft might be needed if the mounting point for it moves. Brake lines kind of worked. Had to use old lines. The ones on the axle were cut.
Edit: truck was previously swapped from 10 bolt to sf 14 bolt and looked like original driveshaft was still in with conversion ujoint

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[RoryH19]

I would guess a shorter driveshaft might be needed if the mounting point for it moves. Brake lines kind of worked. Had to use old lines. The ones on the axle were cut. Edit: truck was previously swapped from 10 bolt to sf 14 bolt and looked like original driveshaft was still in with conversion ujoint

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Ok. Then the driveshaft and brake lines should be good to go.
Were you able to connect the ebrake cables? I think I see it going up to the frame but can't tell for sure.

 

[yevgenievich]

Ok. Then the driveshaft and brake lines should be good to go.
Were you able to connect the ebrake cables? I think I see it going up to the frame but can't tell for sure.

Have not connected the ebrake cables yet. Will get to them eventually.