Considering 2WD -> 4WD conversion (full-size GMT800)

[Reprise]

Entertaining the idea of doing this (as next year's project) for the Sierra; found a 4.10 front diff on CL for not a ton of $.
Need to call the guy tomorrow & ask questions (among them being whether it's the 9.25" ring gear (what came in the HD trucks). He has no pic, but he did respond to my e-mail and I'll call him to chat in the next day or two.

Besides the diff, I know I need:
- both axle shafts
- front hubs
- f/r driveshafts (this one might be tricky, since my current rear shaft is a Dana / Spicer (yeah, really; same as the axle)

- replace output shaft on the 4L80 trans (so it has to come apart, and if doing that, rebuild it (w/ bulletproofing)

- also add tailpiece to connect to t-case​

​

- transfer case (the really expensive item; I want to use a manual t-case with the floor shifter, like the W/T use.) I have the full floor console, so this might require a little 'fabrication', relative to where the floor shifter normally goes.

- connectors, linkage, shift lever, trim bezel, etc.

I don't plan on driving the truck in snow, not gonna lift it, or go off-roading. Pretty much just 'insurance' for getting myself 'unstuck', especially if I'm towing. And the pride in saying "I did it".

Amazingly, I'm at a point in my auto repair knowledge where the work doesn't (!) scare me, not even cutting the access hole in the floor for the shift lever. Maybe I've been watching too many car repair shows?

Yeah, I know it will easily run a couple of thousand to do it in parts alone, plus all the little 'gotcha' items I'll have to pick up along the way. Actually more than that, since I'm rebuilding the 4L80, too.

The other downside is that I'd remove -200lb of towing capacity (and probably lower my gas mileage an additional 1mpg). This doesn't bother me much; I'm not near the limits in either GVWR or payload, and I'm putting a cam in soon (this year's project), so fuel economy isn't a huge concern (14 unloaded and 8-9 towing... what's the difference? LOL)


Would pick up / stash the diff now, as the 4.10s don't come along too often (it's from a 2002; one year apart, no big deal).
Yeah, I could change to 3.73s, but I'd lose 20% of my tow capacity if I did that. Keeping the 4.10

Should I put up a poll and request votes on whether or not to do it?

 

[Mooseman]

Looked at this for my son's 2WD Silvy and it is practically impossible to do without a donor truck beside it. First off, the steering systems in both are different (R&P vs linkage system in the 4x4), the tranny needs to be taken apart to change the tailshaft so basically might as well rebuild, Suspensions are different (coil vs torsion) so frame may not even be able to accept it, steering knuckles, A-arms (frame again), etc, etc, etc.

It might even need a full frame swap to work. Save your sanity as this will just turn into an endless and eventually abandoned project.

 

[Reprise]

That's the kind of feedback I was looking for - thx

As it turns out, I've got the correct underpinnings (linkage, torsion bar, etc.), so it might not be so difficult (I'd never try it with dissimilar chassis', like you mentioned.)

Tempting, but I'll probably pass. It all 'sounds' nice... until you get into it. Plus my own admission that I'd only *use* the finished product in an 'emergency' (so, .01% of the time?)
Lot of time, effort & $ spent, just for 'bragging rights'

 

[Mooseman]

You're welcome!

 

[TollKeeper]

We actually did this on my companies work 2006 2500. The control arms, hubs, torsion, was all the same. Swapped the tranny for one with a TC and needed items, changed the oil pan, installed the front diff, and it was a done deal. We also used a manual TC case. Dont have to worry about the computer or anything else that way.

 

[Mooseman]

You're not helping...

 

[Reprise]

Damn straight he's not!

Besides the 'ease' of implementation, reliability is the reason I wanted to put the manual t-case in. The push-button type works great - until it doesn't.

As it turns out, I'm being tempted all over again. Someone posted an '05 2500hd 4×4 - with manual t-case - for $1500. 180K & doesn't run; needs fuel tank / lines, but otherwise, has everything I need (and more).
I just don't have room to strip it down. Damned HOA

 

[Mooseman]

@Mooseman slapping @TollKeeper