Drop in full float upgrade?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Tachyon

I'm Awesome
Joined
Nov 29, 2017
Messages
110
Reaction score
69
Location
Edmonton
Is anyone aware of an 8-bolt full float rear end that's a drop in replacement for an 8-bolt semi-float on the GMT-400 of course? 3/4 ton.

(I should clarify that by 8-bolt I obviously mean the wheel lugs not the differential cover)
 
Last edited:

Stokes1114

I'm Awesome
Joined
Apr 24, 2016
Messages
120
Reaction score
24
Location
Colorado
Is anyone aware of an 8-bolt full float rear end that's a drop in replacement for an 8-bolt semi-float on the GMT-400 of course? 3/4 ton.

(I should clarify that by 8-bolt I obviously mean the wheel lugs not the differential cover)
As long as the 14 bolt, 8 lug comes from ANY other 400 it will fit. You could end up needing drive shaft work done though, as with most rear swaps.
 

gstubbz

Hi I'm Gavin and I have an OBSession
Joined
May 12, 2014
Messages
1,122
Reaction score
668
Location
CA ⤖ Eureka, MT
From what I can tell all single rear wheel 3500s had full float axles, and on 2500 trucks they were behind 6.5s and 454 trucks.

The 2wd rear axle is 2" narrower than a 4wd axle.

As far as U joints go, you'd probably have good luck with either the 447 or 448 u joint.
 

Chewy1576

I'm Awesome
Joined
Jan 14, 2013
Messages
950
Reaction score
302
Location
Ogden, UT
I swapped a full float from a 1998 K2500 6.5L in place of the semi float in my 1990. Direct swap, no mods needed. I did use a u bolt flip kit instead of the stock setup for an upgrade also.


Sent from my iPhone using Tapatalk
 

Tachyon

I'm Awesome
Joined
Nov 29, 2017
Messages
110
Reaction score
69
Location
Edmonton
Great answers, thanks guys.
Out of curiosity is anyone aware of any non GMT-400 sources that are bolt in?
 

Chewy1576

I'm Awesome
Joined
Jan 14, 2013
Messages
950
Reaction score
302
Location
Ogden, UT
There are some GMT800 full float axles that will swap in. They could have disc brakes standard too.


Sent from my iPhone using Tapatalk
 

Tachyon

I'm Awesome
Joined
Nov 29, 2017
Messages
110
Reaction score
69
Location
Edmonton
There are some GMT800 full float axles that will swap in. They could have disc brakes standard too.


Sent from my iPhone using Tapatalk

That's what I was wondering. Hmm. ..too bad these trucks don't have adjustable brake balance.
 

Tachyon

I'm Awesome
Joined
Nov 29, 2017
Messages
110
Reaction score
69
Location
Edmonton
I swapped a full float from a 1998 K2500 6.5L in place of the semi float in my 1990. Direct swap, no mods needed. I did use a u bolt flip kit instead of the stock setup for an upgrade also.

BTW. About how much lift did the flip kit give you?
 

someotherguy

I'm Awesome
Joined
Sep 28, 2013
Messages
9,784
Reaction score
14,138
Location
Houston TX
Stick with a GMT400 rear and drums. Drum brakes work great (especially those BIG ol' drums on a full floater 10.5") and you won't have the issues some of those disc rear GMT800 trucks had.

Also FYI in the 2500's it was more typical to find a full float in the 96-up trucks; a lot of the earlier 2500's got semi float.

Richard
 
Top