Gmt900 14 bolt rear swap questions

09SierraZ71 · December 2, 2017

Hi all, looking to upgrade to the 14 bolt rear end. I read that the new k2xx series has the 9.5" rear end from the factory with all v8's that don't have the max trailering pkg.

Does anyone know if the k2xx rear end fits the gmt900, including working abs, stabilitrak.

thanks in advance

carnau · December 3, 2017

20 hours ago, 09SierraZ71 said:

Hi all, looking to upgrade to the 14 bolt rear end. I read that the new k2xx series has the 9.5" rear end from the factory with all v8's that don't have the max trailering pkg.

Does anyone know if the k2xx rear end fits the gmt900, including working abs, stabilitrak.

thanks in advance

Ok this is something I am actually doing right now on a K5 blazer and it is a total freaking nightmare. I know what you are doing is going into something newer but my K5 is having so many unintentional lockups they I am trying to resolve that I am thinking about going to a 9in like I should have done from the start. I can only imagine the issues you would have trying to sync an ABS system to it with all the problems I am having with absolutely no ABS, but then again that could be my issue.

What I will say is good luck and I am very curious to know how it works out. If you need any specs or load tensions let me know and I can get those for you.

09SierraZ71 · December 4, 2017

appreciate the reply, yea i haven't got really any info on them. The 07-13 gmt900 6-axle 14 bolt is almost impossible to find, especially in 3.42 (my current ratio). Seems only rwd 6.0L and 6.2L 07-13 trucks have the 14 bolt whereas the 4wd 6.0L and awd 6.2L (denali) have the 10 bolt with rear dics. Then i looked under a couple k2xx trucks (14+ )and saw they had the 14 bolt (9.5" ring gear) under standard equipment. I don't think gm would change up the whole line-up for the abs/ wheel speed sensors but i don't want to get myself into something that isn't relatively bolt in. On my other cars i have time to experiment but this is my dd and i cant afford to have it down. If anyone else could chime in i'd appreciate it.

Hayesg · October 6, 2023

I , too am looking to do this swap. The 9.5 Hybrid with disc brakes (JD9) and 4.10 gears (GT5) and LSD (G80). I have the 8.6 with 3.42’s and drums. I have found that the only difference as far as the brakes is the master cylinder. As for the ABS system, I am in the dark. I know the GT4 package (3.73’s) were available for 07-13. However the GT5 package can only be found in the 9.5 hybrid from 07-08. I know that a U-Joint conversion is needed to go from an 8.6 to a 9.5 Hybrid. I am wondering if the 07-08 also have ABS. As long as the tone wheels are the same tooth count in the axle, I don’t see the issue. I don’t want to get an axle and lose ABS and Stabillatrak. 35’s, drums, towing and 3.42’s aren’t a great combination and looking to make a “Heavy Half Ton”. Any insight here would be greatly appreciated.

swathdiver · October 7, 2023

You should not need a conversion joint, they all run 1355 u-joints AFAIK. 3.42 gears are more plentiful but you can find some 3.73s (2009.5+ NHTs). 4.10s would be quite rare, they were used behind 6.0 L76 with 4L70 trans with NHT package.

Do you have a 4-speed or a 6-speed?

Hayesg · October 7, 2023

I have the 6L80 6 speed. I was wanting to upgrade axles without having to change gears. Do you happen to know about the speed sensors in the 14 bolt?

swathdiver · October 7, 2023

6 hours ago, Hayesg said:

I have the 6L80 6 speed. I was wanting to upgrade axles without having to change gears. Do you happen to know about the speed sensors in the 14 bolt?

Ok, you have one of the later year 2009s. 3.42s are good for towing, it's equivalent to 4.10s in a 4-speed truck.

Anyhow, the wheel speed sensors bolt right up to the 14-bolt. The tubes are the same, same seals, bearings and tone rings are the same, even the parking brake mount and backing plates.

209138122:

Your existing sensor will bolt right up to the 14-bolt.

Edited October 7, 2023 by swathdiver

Hayesg · October 8, 2023

So ordering a 07-08 14 bolt hybrid with the GT5 package shouldn’t be a compatibility issue? That will help me nail down the last of my plans to do the swap. The front carrier swap is straight forward.

swathdiver · October 8, 2023

6 hours ago, Hayesg said:

So ordering a 07-08 14 bolt hybrid with the GT5 package shouldn’t be a compatibility issue? That will help me nail down the last of my plans to do the swap. The front carrier swap is straight forward.

Some early 2009s had them too. No compatibility issues. How are you going to order one? I've only found them on LKQ searches and bought two.