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Old 10-09-2018, 04:30 PM   #1
72-k20-burb
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6.0 LS swap header fitment issues

Hi folks,

long time reader, first post.

I bought a 72 k20 suburban a few months back, and have proceeded to tear out the old power plant and put in a low mile l96 (6.0). I got the old np205 on the back still and it's in the stock mounting location.

I'm using the dirty dingo 4x4 crossmember kit with clamshell mounts.

The stock manifolds on the 6.0 did not work, and I just bought THY-323Y-C doug thorleys and they wont work. Ah!

I checked throley and summit, both sites make it seem like they should fit. Is everyone using slider mounts to move the motor back? I'm hoping to avoid that so the trans and drive shafts all stay in stock locations.

Are there other headers I should get that will clear? I checked the thorley 324s and they have the same fitment listed online. At $650 a pop I don't want to cut these up to make them fit unless absolutely required.

Thanks!

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Old 10-09-2018, 08:26 PM   #2
mongocanfly
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Re: 6.0 LS swap header fitment issues

Welcome....
I got sucked into that "they should fit" thing...I wound up using headers for a hummer...but I would never recommend anyone do this...it took a ton of modifying to make it work...if I was doing it over I would probably use LS3 manifolds...I think those would work..and it being a K series will make it even more difficult to dodge driveshaft,axle and such
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1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563

Last edited by mongocanfly; 10-09-2018 at 10:19 PM.
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Old 10-09-2018, 08:45 PM   #3
72-k20-burb
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Re: 6.0 LS swap header fitment issues

The LS3 exhaust manifolds look pretty darn close to the ones that came on the l96. Do they hug tighter than other manifolds?

Dirty dingo has 1302LS1-C Schoenfeld headers that supposedly work for 4x4, however they won't call me back after a few voicemails. I already spent enough money there I would have hoped for better service.

I read a few people here used Speed engineering, they have a note that says no 4x4..

Getting custom exhaust made seems simple enough to clear the 4x4 transfer case if I can first clear the frame... I'd really rather not cut or modify like you said.
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Old 10-09-2018, 10:19 PM   #4
mongocanfly
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Re: 6.0 LS swap header fitment issues

I'm not sure what the L96 mani looks like...
Here's the diff between a 5.3 and a LS3 mani...the 5.3s stick out from the engine about 3/4" more than the LS3
Attached Images
  
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Mongo...aka Greg

1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563

Last edited by mongocanfly; 10-09-2018 at 10:28 PM.
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Old 10-09-2018, 10:25 PM   #5
CJM72
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Re: 6.0 LS swap header fitment issues

We should trade! I have a set of THY-324Y-C headers that fit inside the frame rails fine, but basically were rubbing on the firewall on the driver's side. If you have clearance in that area, these might work for you. Too bad we weren't closer, or I'd let you try to fit them. I could have just hammered a dent in the firewall, but I didn't want to do that. Almost bought the 323y's as I've seen others fit them just fine.

https://boston.craigslist.org/sob/pt...719481365.html
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Old 10-09-2018, 10:29 PM   #6
CJM72
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Re: 6.0 LS swap header fitment issues

For the record, I have the same Dirty Dingo crossmember with a 6.0 and a 4l65e adapted to the np205. Left the NP205 in the stock location, but I have a k5. It's too bad, these headers tuck up nicely, cleared the frame, spring shackles, and look great.
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Old 10-09-2018, 10:42 PM   #7
mongocanfly
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Re: 6.0 LS swap header fitment issues

CJM.....So the LS3 manis fit ok?..
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Mongo...aka Greg

1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 10-09-2018, 10:48 PM   #8
72-k20-burb
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Re: 6.0 LS swap header fitment issues

Thanks for the comparison Greg, I'll upload a picture of the l96 ones for future reference.

Quote:
Originally Posted by CJM72 View Post
For the record, I have the same Dirty Dingo crossmember with a 6.0 and a 4l65e adapted to the np205. Left the NP205 in the stock location, but I have a k5. It's too bad, these headers tuck up nicely, cleared the frame, spring shackles, and look great.
Is the k5 front frame geometry any different from the c10/k20 etc?

What 6.0 do you have and what headers did you end up using? I've heard these 323s fit with the LQ9/4s so that's why I bought them hoping it would be the same for the l96 6.0.

The photo from your craigslist ad makes it look like your motor sits pretty similar to mine. I'm tempted to send mine back to summit now and get those 324s. I only went with the 323s over the 324s because of the 1-7/8 sizes primaries.
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Old 10-09-2018, 10:51 PM   #9
mongocanfly
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Re: 6.0 LS swap header fitment issues

I've also got a set of manis off my LQ9 and they are the same as the ones from the 5.3
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Mongo...aka Greg

1981 c30 lq9 nv4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598
1955.1 ls3 tr6060...(under construction)(on hold)
2013 gmc z71. (daily driver)
Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563
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Old 10-09-2018, 11:11 PM   #10
CJM72
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Re: 6.0 LS swap header fitment issues

Quote:
Originally Posted by mongocanfly View Post
CJM.....So the LS3 manis fit ok?..
Yup, fit great. I have them bolted in there now! Just would like to have headers.
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Old 10-09-2018, 11:16 PM   #11
CJM72
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Re: 6.0 LS swap header fitment issues

Quote:
Originally Posted by 72-k20-burb View Post
Thanks for the comparison Greg, I'll upload a picture of the l96 ones for future reference.



Is the k5 front frame geometry any different from the c10/k20 etc?

What 6.0 do you have and what headers did you end up using? I've heard these 323s fit with the LQ9/4s so that's why I bought them hoping it would be the same for the l96 6.0.

The photo from your craigslist ad makes it look like your motor sits pretty similar to mine. I'm tempted to send mine back to summit now and get those 324s. I only went with the 323s over the 324s because of the 1-7/8 sizes primaries.
Looking at the pictures in my thread, the cross member and motor location look identical. I believe the 4x4 trucks all have same frame geometry up front. You can see where mine driver's header was touching the firewall. Couldn't even slide a piece of paper in there!
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Old 10-15-2018, 04:04 PM   #12
DWilbur
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Re: 6.0 LS swap header fitment issues

The DD engine mounts don't work with LS 4X4 swap. The issue is the mounts set the engine 1-1/2" lower that 2 wheel drive LS swap. In the end I modified my Dough Thorley Headers had to rework the front header tubes on both sides to clear the frame so they fit.
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