I blew up the stock 10 bolt in my truck with the stock 5.7 (has headers and CAI) so it wont last behind a lq9. I swapped in a 9.5 14 bolt and it was super easy, pretty much just bolted right up you just need a conversion u joint and you keep the 6 lug bolt pattern. I have a trutrac locker with Richmond 373's. there is nothing you can do about the front diff unfortunately unless you want to solid axle swap it, there is 0 aftermarket items for the front half ton diff/axles.

don't waste your time keeping the 700r4, go 4l80e which you can most likely get with the lq9 as that's what they came with from the factory. you can use the full wiring harness from the donor vehicle that way and not have to mess with standalone trans harnesses and such. I have the full drive train out of a 2001 2500 truck (lq4, 4l80e, tcase) that I will be swapping in my 96 k1500

 

If the trans is built to withstand the new power, what is keeping the LQ9 from working with the 700R4? Is it fitment, or function? What sort of headaches am I looking at to get a matching transfer case for the 4L80E bolted up to the truck, am I looking at custom driveshafts or would something like the shafts off a 2500 with that trans and transfer case work? For reference, the 700R4 I'm going with is a stage 2 4x4 700R4 from Gearstar, it's rated for a fair amount over what I aim to be making on the new engine. I guess that's why I'm confused, it seems to be good for holding the new power, it's a mechanical trans anyways so getting it to work with the LQ9, at least as far as I can see, should just be a matter of using the same kind of DBC throttle the truck already uses and hooking up the tv cable to it correctly, making sure there's enough tension on the cable so it doesn't burn up the trans, and making sure the correct adapter from flexplate to converter is installed. In theory, it seems pretty straightforward, so what makes the 700R4 so bad a trans for this build? It has a lower first gear ratio, and a slightly higher 4th gear ratio than the 4L80E, 3rd is the same in both, though the 4L80E has a higher 2nd gear. How difficult is it to swap a 4L80E and the accompanying components that'll let me keep 4x4 in this truck as compared to the equipment already in it? If they're both built to hold the same power, is the benefit then only trans tuning?

If I go with a 4L80E, is there anyone that can recommend a shop here in Texas to have it rebuilt at? Any trans coming with and of the LQ9's I'm looking at will likely have as much mileage as the engine, and 100k miles is a lot of wear on those clutches.

Also, just to make sure I'm understanding this, are the 9.5 14bolts only available for the rear, or are there 9.5's for the front too that I can use instead of swapping to a solid axle?

I don't mean to be dense, but I'd like to get as much information about this as I can so I'm not losing money making mistakes on what to get. Thanks for the help so far y'all!

 

No 9.5's for the front. The front is an ifs 8.25". The obs 3/4 ton trucks use an ifs 9.25" in the front which is much stronger, but I've never tried to swap one into a 1/2 ton truck.

 

 

As long as both gear ratios are the same you can run a bigger rear with the original front.

 

Trutrac is shitty for offroad, and basically worthless in the snow. Take a look at my sig and ask me how I know.

For a street car I would 100% love this unit, but the more slippery the conditions the worse this thing performs. Exact opposite of what you need in an off road situation.

OP - as someone else pointed out, you're kinda fucked on the front end as far as stronger parts go. You CAN put an aftermarket "posi" unit in it, but unless you're doing heavy offroad stuff you probably want to steer clear of doing so.

Just put an aftermarket carrier in the rear, new gears on both ends and you're fine.

 

 

 

SOMETIMES, though not always as they get lost, there is a metal tag on one of the bolts on the center section with the ratio.

 

RPO codes are in the glove box. Should be a letter "G" designation to start with...such as "GU6" GU4"...

If you see a G80, this is the RPO for a posi rear diff.

EDIT: There won't be any "tags" on either of your diffs, so don't wast time looking for them.

 

And while i have a little spare time to sit here and reply, get the engine swapped and running before you put so much time and worry into your differential situation.

Seriously, you'll have plenty of much more important things to worry about in this swap long before you have to even think about those diffs...

Get it up and running, work the bugs, have a little fun with it. Worry about those diffs when, and if, they give you trouble..

 

I'm suggesting the 4l80e because you won't have to build it at all to hold the power you are looking for. if you get a donor vehicle you will have the whole drivetrain to just drop in your truck and you can sell the 700r4 to recoup some money. like said above there isn't any aftermarket for the front diff, either solid axle swap or leave it alone, just don't do any 4wd launches and it will live. you most likely have 373's, that's what came in my truck from the factory so I just looked for a 373 9.5" 14 bolt and swapped it in after blowing up my 10 bolt.

RPO codes are in the glovebox like CattleAc said

 

 

 

 

RPO is GT4. Googling comes up with the 3.73 rear end. If I swap to a 9.5 in the future I’ll search around for a 3.73. Thanks for the help y’all!

 

depends on the tcase that's behind it. my truck was a push button from the factory unfortunately so I have a tcase that is push button to go behind the 4l80e. if you want to keep the manual 4x4 (which you should cause bush button sucks) just look for a truck that has it if you are looking for a donor truck. I cant remember off the top of my head what tcase I have but there were two available behind the 4l80e's, manual and electronic. just need to find the manual one.

edit: quick google search and I have a NV263 which is the electronic shift tcase, the manual shift is NV261 which is the one you'd want. comes in 2001+ 3/4 and 1 ton trucks.