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Discussion Starter #1 (Edited)
Looking to upgrade motor/tranny on my 2006 LJ, I found in a local yard a 2014 Chevy Caprice with the POLICE package. Motor is a 6.0 with a 6L80 transmission.

I've been looking at Escalades and Silverados for the 6.x and 6L80 transmission but this Caprice seems to have what I need.

What you LSX gurus think about that transmission out of the Caprice?

Is it the same as in the 2500 HD Silverados? And the Escalades?

Has this Caprice 6L80 have any Advantage/Disadvantage over the other donor transmissions above?

Please let me know.
 

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it's basically the same motor as the G8, but has VVT like the truck L76 and E85 compatible. So basically the same thing as a 08 1500 with the vortec max. 6L80E is proven. Yes, it's a good setup
 

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Mind you, the Caprice will have a 2wd transmission so make sure you account for changing it to 4wd or running a divorced t-case.
 

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Discussion Starter #4
Interesting.... I thought I would need to just eliminate the skip yoke on that 2wd tranny and bolt the transfer case... but I guess I would need a pricey adapter to convert that transmission into a 4wd?

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Discussion Starter #6 (Edited)
A complete pull out including engine with all accs, ecm, harnesses and transmission is $5,000 at the yard. I'm looking to spend that less for the entire salvaged car or a totaled Escalade with the 6.2
 

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Discussion Starter #8
Thanks for input.. but that listing does not include the 6L80 transmission... that's $1,300 the least value...
 

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Interesting.... I thought I would need to just eliminate the skip yoke on that 2wd tranny and bolt the transfer case... but I guess I would need a pricey adapter to convert that transmission into a 4wd?

Sent from my SM-N910T using Tapatalk
I'm not familiar enough with the construction of the 6L80E to comment on if this would work or not. I seem to recall that the RV style 4L80E had long enough splines that you could just remove the slip yoke tail housing from the 80E, cut down the splines and it would work - but I'm not 100% on that for the 4L80E and especially not for the 6L80E.

Most likely even if the slip yoke housing does come off, you'd need a full transmission tear-down to replace the output shaft with a shorter shaft designed for 4wd use. I may be wrong though; it would be easy to check if you already had the 6L80E.
 

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No offense, but that was very inconclusive lol. I was curious about this swap as well being that 6 speed should have better gear ratios, and it's plenty strong for anything I'd want to do.
post #6

The question was about converting to 4wd, same as 4L60e, swap output shaft, swap tail section.


First: 4.02
Second: 2.36
Third: 1.53
Fourth: 1.15
Fifth: 0.85
Sixth: 0.67

edit:

Here's a spoonfed writeup, took all of 45 seconds of searching...

http://www.jkowners.com/forum/write-up-dept-library/209266-gm-6l80e-2wd-4wd-conversion-ls-jk-swaps.html
 

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post #6

The question was about converting to 4wd, same as 4L60e, swap output shaft, swap tail section.


First: 4.02
Second: 2.36
Third: 1.53
Fourth: 1.15
Fifth: 0.85
Sixth: 0.67

edit:

Here's a spoonfed writeup, took all of 45 seconds of searching...

GM 6L80E 2wd to 4wd conversion for LS JK swaps - JKowners.com : Jeep Wrangler JK Forum
I wasn't looking for a write up at all, nor am i ready to do this. Just curious if the swap had gained any traction. I would've searched and found the other thread if/when i was ready. I figured a tail shaft/tail section swap was necessary, just hoping i could cut tail shaft and get the tail section needed, but to my dismay it is more involved than i hoped for. I have a 2wd 6l90e with 6.0 liter in front of it, but not sure i'm keeping atm...maybe just maybe lol
 

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Keep in mind the truck 6L90Es had a slip yoke, so I'm not sure how that affects swapping it to 4wd from 2wd.

This is more a comment for those in the future wanting to do this swap. It looks like the spoonfed write-up will work for OP.
 

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Keep in mind the truck 6L90Es had a slip yoke, so I'm not sure how that affects swapping it to 4wd from 2wd.

This is more a comment for those in the future wanting to do this swap. It looks like the spoonfed write-up will work for OP.
Not to keep this going too far, but are you saying that since the hd truck trans (6L90e) is 32 spline and slip yoke, there's a chance that it may work? I guess on the other thread, and this one for that matter, i missed the fact that they were dealing with car transmissions. It seems that the 1/2 ton trucks in 2wd came with a different spline too then?
 

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Not to keep this going too far, but are you saying that since the hd truck trans (6L90e) is 32 spline and slip yoke, there's a chance that it may work? I guess on the other thread, and this one for that matter, i missed the fact that they were dealing with car transmissions. It seems that the 1/2 ton trucks in 2wd came with a different spline too then?
As far as I know, there are four 6L90E transmissions available.
  • 2wd w/ fixed output flange (G8 GXP, Holden Commodore SSV, and the Camaro ZL1)
  • 2wd w/ slip yoke output flange (trucks)
  • 2wd w/ parking brake output flange (Isuzu 6.0L Med Duty Trucks)
  • 4wd
I'd be surprised if they weren't all the same spline output, but something seems to stick out in my mind from when we were selling these at my last job that at least the 2wd parking brake output was 34 spline. However, a build thread on performance trucks states that the flange and slip yoke outputs were both 32 spline (but with a larger bushing diameter, so a normal 4L80E yoke will slide on but ultimately not work). I think these parking brake transmissions were rated at a higher GVW, so it's possible that it does, indeed, come with more splines than the standard 2wd transmissions, but I think that would be odd so maybe I'm mistaken.

It also looks like the 6L90E 4wd are 29 spline, based on Advance Adapters' Atlas Install instructions. I'm guessing this has to do with commoninzing transfer cases with the Allison. http://www.advanceadapters.com/downloads/509600.pdf

It also sounds like all 6L80E transmissions are 32 spline and the same OD slip yoke (if 2wd) as a 32-spline 4L80E 2wd/NP241/NP246/NP261/ETC.

Clear as mud?
 

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But if you are swapping the output shaft to a 4 wheel drive output it shouldn't matter which version of the 2wd trans you have? I can't see the tail section bolt pattern being different on the 4 versions, just the output shaft and yoke.
 

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As far as I know, there are four 6L90E transmissions available.
  • 2wd w/ fixed output flange (G8 GXP, Holden Commodore SSV, and the Camaro ZL1)
  • 2wd w/ slip yoke output flange (trucks)
  • 2wd w/ parking brake output flange (Isuzu 6.0L Med Duty Trucks)
  • 4wd
I'd be surprised if they weren't all the same spline output, but something seems to stick out in my mind from when we were selling these at my last job that at least the 2wd parking brake output was 34 spline. However, a build thread on performance trucks states that the flange and slip yoke outputs were both 32 spline (but with a larger bushing diameter, so a normal 4L80E yoke will slide on but ultimately not work). I think these parking brake transmissions were rated at a higher GVW, so it's possible that it does, indeed, come with more splines than the standard 2wd transmissions, but I think that would be odd so maybe I'm mistaken.

It also looks like the 6L90E 4wd are 29 spline, based on Advance Adapters' Atlas Install instructions. I'm guessing this has to do with commoninzing transfer cases with the Allison. http://www.advanceadapters.com/downloads/509600.pdf

It also sounds like all 6L80E transmissions are 32 spline and the same OD slip yoke (if 2wd) as a 32-spline 4L80E 2wd/NP241/NP246/NP261/ETC.

Clear as mud?
Yes, very clear lol!
So if using a 2wd truck trans, it may bolt up to a 32 spline np241...but the 4wd trans may only be 29 spline due to the Alison trans being 29 spline. Still might have to change out the tail shaft, and definitely change the trail section.

But if you are swapping the output shaft to a 4 wheel drive output it shouldn't matter which version of the 2wd trans you have? I can't see the tail section bolt pattern being different on the 4 versions, just the output shaft and yoke.
The way I'm reading it, it may only need to be swapped if you're using a car trans? The 2wd truck trans may have a long enough spline to trim, but that is the unknown. I guess i could pull the tail section off my hd the next time I'm pulling the drive shaft (have to change mid ship, so not too much to ask imo) to check spline length. Again, all speculation on my part until all the above is confirmed lol....
 

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But if you are swapping the output shaft to a 4 wheel drive output it shouldn't matter which version of the 2wd trans you have? I can't see the tail section bolt pattern being different on the 4 versions, just the output shaft and yoke.
The goal here is probably to not have to change the output shaft on the transmission, since that would require a full rebuild.

Yes, very clear lol!
So if using a 2wd truck trans, it may bolt up to a 32 spline np241...but the 4wd trans may only be 29 spline due to the Alison trans being 29 spline. Still might have to change out the tail shaft, and definitely change the trail section.



The way I'm reading it, it may only need to be swapped if you're using a car trans? The 2wd truck trans may have a long enough spline to trim, but that is the unknown. I guess i could pull the tail section off my hd the next time I'm pulling the drive shaft (have to change mid ship, so not too much to ask imo) to check spline length. Again, all speculation on my part until all the above is confirmed lol....
Pretty confident that Advance Adapters isn't wrong, so I'm pretty damn certain the 4wd 6L90E will not work with a 32 spline input transfer case - without swapping the trans output shaft.

But yes, I think you're correct. Make sure you also count the splines on your truck the next time you have the driveshaft out!
 

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The 6L80 uses a 32 spline output shaft in the 4WD and 2WD model transmissions. Transmission length 23.2"
The 6L90 uses a 29 spline output shaft in the 4WD. Transmission length 24.6"

It looks like you can use the 2wd trans and cut the output shaft, at least for an atlas.
http://www.advanceadapters.com/downloads/509600.pdf
 
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