1994 K3500 extended cab dually

[n8in8or]

Nice work! the only thing I would be worried about for the future is the flex joints. when the day comes they start leaking and you need to replace. iirc they make them with v band flanges so that they could easily be replaced, wonder if you have clearance for that though.

Though on my 95 I just about had no choice to cut my down pipe and splice in a 4" steel flex pipe to alleviate the stress and from it banging the frame to the 4" exhaust kit I installed. It's been on there for a while now, all rusted but still holding up LOL. your stainless should last for years to come!

As long as I make my cuts straight, it won’t be bad to replace them in the future if the need ever comes.

 

[n8in8or]

It took 2 days, but I finally have the post-turbo exhaust done (mostly).

I installed an FTE Diesel muffler/resonator on it again because the sound was great and I had zero drone in the cab. It’s 409 stainless.



All tubing is 304 stainless. I started TIG welding all the joints. Oof. That took so long and I wasn’t happy with the results - not only did my beads look like crap, but I’m also not set up to backfill the tubes with argon, so I wasn’t getting great corrosion resistance anyway…..so I ended up welding all the joints with carbon steel MIG and was much happier with the results. The downpipe starts 3” and transitions to 4” before the flex joint. I left the end of the exhaust unfinished so I can make the tip align with the bed how I want and not have to rework it after the bed is installed…..I learned that lesson on the red truck.

 

[n8in8or]

Remote oil filters are installed. I used a Canton remote oil filter adapter and Fragola -10 AN lines and fittings. I bought the oil filter mount a while ago and can’t remember the brand.

 

[n8in8or]

This evening I loaded the chassis up and took it to a local cruise-in, just for funsies. Also had to pop the hood on the Tahoe.

 

[MrMarty51]

This evening I loaded the chassis up and took it to a local cruise-in, just for funsies. Also had to pop the hood on the Tahoe.

View attachment 95886View attachment 95887View attachment 95888

I’d think that would have got quite a bit of attention from the true enthusiasts.

 

[n8in8or]

I sandblasted the manifolds and hit all the welds on the rest of the pipes with a stainless wire wheel. After that I painted the manifolds, crossover pipe, down pipe and resonator/muffler with KBS Xtreme Temperature Coating. And finally I wrapped the crossover and downpipe with DEI header wrap. I installed the manifolds with Stage 8 header bolts so they won’t loosen up. I also wrapped the starter with some heatshield material I had in stock already. It’s ready for the cab to be installed now.

 

[dbrannon79]

Nice!!

question, how low does that crossover hang (from the ground) I assume you are planning for suspension lift or tall tires for offroad shenanigans.

 

[Twisted Steel Performance]

Ya gonna wrap the manifolds ? That would really keep heat out of the engine bay...

 

[n8in8or]

Nice!!

question, how low does that crossover hang (from the ground) I assume you are planning for suspension lift or tall tires for offroad shenanigans.

The crossover isn’t any lower than the diff skid plate so it’s ok. The pics are deceiving.

 

[n8in8or]

Ya gonna wrap the manifolds ? That would really keep heat out of the engine bay...

I’d like to wrap them, but the old manifold was rusting under the wrap so I didn’t want to promote that happening again.

 

[dbrannon79]

you can always keep the ones you just made as spares/mockup units and re-make them with any added design changes from stainless, then wrap those LOL

 

[n8in8or]

I’d really like to have the hot side coated in this stuff, but it isn’t cheap so I’d need to make sure my design all works how I want before I make that investment. If I am happy with it, I could blast the stuff and send it to them or make a new setup and send it to them for coating. This way I have heat containment without wrap that will trap moisture between it and the tubing. I was turned on to this stuff when I was working on building up the 460 in the Class C motor home we had - it’s supposed to do a great job of taming heat when applied to headers in that application.

White Lightning Exhaust Coatings – Swain Tech Coatings | Industrial Coatings | High Performance Racing Coatings

 

[n8in8or]

Got the cab on today. Took longer than I anticipated, but the task is done.



Unfortunately I found that the downpipe hits the cab - even when it’s detached from the turbo. I thought I was going to have tons of room with where I put it and have the best heater hose situation I’ve ever had, but I guess I screwed up, so downpipe mods upcoming.

 

[dbrannon79]

Nice work! wonder if you were to custom make a sharp 90 with flanges on both sides, then tweak the down pipe if that would give you some extra clearance.


something I have always wondered... on these gmt400's what it would take to convert to a short bed. I keep picturing in my head of my 93 CC LB getting a short bed.

 

[n8in8or]

Nice work! wonder if you were to custom make a sharp 90 with flanges on both sides, then tweak the down pipe if that would give you some extra clearance.


something I have always wondered... on these gmt400's what it would take to convert to a short bed. I keep picturing in my head of my 93 CC LB getting a short bed.

I’m going to mockup the core support and inner fender, plus put the AC line in place so I can truly see what my envelope is and then optimize the downpipe to fit. I’m still shocked how tight it is. I think the way I did the #8 tube ate into my space more than I understood.

 

[MrMarty51]

Nice work! wonder if you were to custom make a sharp 90 with flanges on both sides, then tweak the down pipe if that would give you some extra clearance.


something I have always wondered... on these gmt400's what it would take to convert to a short bed. I keep picturing in my head of my 93 CC LB getting a short bed.

I would like to find an extended cab with the short box, whatever length they came with.
Saw off the extended portion of that cab. Saw off the back portion of My CC, weld on the extended portion of the extended cab onto my CC then install that shorter box.
Be like a super crew cab with room for lots more tools and .
I think maybe the short box might be the exact length for a perfect fit.

 

[dbrannon79]

I would like to find an extended cab with the short box, whatever length they came with.
Saw off the extended portion of that cab. Saw off the back portion of My CC, weld on the extended portion of the extended cab onto my CC then install that shorter box.
Be like a super crew cab with room for lots more tools and .
I think maybe the short box might be the exact length for a perfect fit.

GMT400 limo edition!

 

[MrMarty51]

GMT400 limo edition!

Be the only one in town.

 

[Twisted Steel Performance]

So how is the down pipe mod coming?

 

[n8in8or]

So how is the down pipe mod coming?

Ummm…..more difficult than originally thought.

First, I went out Sunday to get started. First thing was moving the truck over to my project stall. I don’t remember what got me under the truck, but when I did get under there I noticed I had more issues than just the downpipe - there was exhaust interference due to a brace under the cab that I didn’t remember or see when I was building the exhaust.



So that day and the beginning of the week was reworking that part of the exhaust. That was depressing, all of that time wasted. Building the exhaust was so much better without the body in the way, bit it also gave me an incomplete picture of all of the obstacles to clear the 4” exhaust. I have it rerouted and tacked together now.



So then I started focusing on the downpipe finally. I got the inner fender and AC line in place. There’s a clear shot to the flexpipe, but I didn’t love how the pipe, especially at the turbo, was turning out with the stuff I have on-hand. I’m waiting for more exhaust parts and the critical part might be here Sunday.