50' GMC 5 window, my first build
 

Hey everyone, I have started my first full build a few weeks ago. I picked up a fairly solid GMC half ton from PA after nagging the owner to sell it to me for months. It's a Colorado truck, killer patina, 5 window, all original.
Since its arrival to me, I've got the motor and trans pulled, front suspension stripped, and most of the unnecessary original parts torn off. Next step (after buying a welder), is to get my mustang II front end. my ultimate plan is to do full airride, 5.3 motor backed by a T56, and clean up the interior.
I will have many questions along the way and appreciate everyone's input in advance. My first set of questions is going to involve how to build a completely new rear frame section from the rear of the cab back. I want to use 2x6 square tubing and make a custom step notch. Does anyone have measurements for something like this? Also wondering what thickness of tubing I will need.
Here are some pics of the progress so far. Please be patient with my build thread, as I am saving for parts as I go and will not have new parts arriving at my door step daily.
Also, can someone school me on how to add more than 1 picture at once using my iPad? It's not working I well for me haha

Re: 50' GMC 5 window, my first build
 

Front

Re: 50' GMC 5 window, my first build
 

Back

Re: 50' GMC 5 window, my first build
 

Tear down

Re: 50' GMC 5 window, my first build
 

Current state

Re: 50' GMC 5 window, my first build
 

Hey 49, posted on the other thread, welcome to the group, moving right along...Jim

Re: 50' GMC 5 window, my first build
 

gotta love those :gmc2:

Re: 50' GMC 5 window, my first build
 

Thanks Jim, the tear down has gone smooth so far. I have a lot of rivets to drill out now so I cant wait for that! Unfortunately i need to buy a welder, cherry picker (the one I used was borrowed from work), and I am about to build a rolling cab stand, and a device to pull the cab off....so progress will not be full force as I would like it to be. All in due time I suppose

Re: 50' GMC 5 window, my first build
 

Welcome 49! Looks like a fun project. You asked about posting more than one picture at a time from the Ipad. I haven't been able too either. I can upload a second picture for the same post and it simply replaces the first uploaded picture. Don't know the reason

What are your plans and goals for the rear frame section? Lots of folks here can help with advice on good ways to achieve those goals.

Re: 50' GMC 5 window, my first build
 

Yeah that's the same thing I was dealing with. Just wanted to make sure I wasn't doing it wrong and being a typical "noob".
I saw another member on here that built a custom rear frame section with a large step notch. He used 2x6 square tubing, and replaced everything from the rear of the cab back. I saved his thread on my computer so will have to look that up and reach out to him about it. I was curious about the dimensions of it, and how to locate the rear axle center line once the rear section is hacked off. I suppose I need to find a reference point somewhere on the frame close to where I will be cutting, and measure the current center line from that point. Then just make sure the new center point is that same distance.
Also, I was getting mixed answers on locating the front center line. The best advice I found was to bolt up the front fenders, stick the wheels in place (centered with fender), and stick a long rod from wheel center to opposite wheel center, and mark it. The problem is I don't yet have the wheels I will be using. Any tips on that?
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Re: 50' GMC 5 window, my first build
 

Welcome.........nice looking project!!

Re: 50' GMC 5 window, my first build
 

That process of centering the front suspension will work fine. And manufacturers of the suspension system typically have good instructions for doing so.

Is the rear part of your frame in bad shape? These trucks will go pretty low with a C notch since the running boards hang below the frame.

I actually haven't inspected the rear of the frame yet, although I should have. Once I get the bed off I will give it a good look. I'm assuming they tent to rust near the leaf spring shackles? Based on the overall condition of the truck I'm thinking it will be fine. The only reason I thought creating a new frame section would be nice is because then it would all be boxed. I'm not sure what parts of the frame take the most pressure. A c notch would definitely be easier for me considering my lack of welding and fabricating skills. If you think that would be safe and strong enough to do, given that the frame is ok, what notch do you recommend? I was looking at the welder series online...
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Re: 50' GMC 5 window, my first build
 

I used a section of 4" pipe to put a notch in my existing frame after I boxed it with plate steel...3/8" I think.

Here is a good read on strength of such a notch. http://67-72chevytrucks.com/vboard/s...d.php?t=457037

After understanding this information, I would go back and build a small bridge section on top of the frame rail to provide additional support. I remember Ogre did that on his truck.

Search C notch and you will see a number of discussion threads. It may get you where you want to be with your truck with a lot less work and fabrication. There is plenty to do all around on one of these builds.

Re: 50' GMC 5 window, my first build
 

Cool thanks, I'll do a little more homework and see what I come up with. Thanks for the link

Re: 50' GMC 5 window, my first build
 

looks good man. gonna be a sick build for sure. ive done notches on bagged mini trucks and full sizes and ive always used 1/4 inch wall 2x4 or 2x3 and ive always laced my joints at any angle on the notches and where Id join the to the original frame and towed with most of them

Re: 50' GMC 5 window, my first build
 

I know one way to lace a joint :smoke: Is that where you weld on a flat piece of steel where 2 pieces are joined to give it extra strength?

Re: 50' GMC 5 window, my first build
 

yes, also called a fish plate. Typically a diamond shaped piece of steel welded over the joint.

Re: 50' GMC 5 window, my first build
 

Here is a picture of how Ogre reinforced his C notch that I mentioned in one of the posts above.

Re: 50' GMC 5 window, my first build
 

Nice progress!

Re: 50' GMC 5 window, my first build
 

unfortunately life has been getting in the way of my project, hence the lack of recent updates. But I've been picking away here and there, and finally have disassembly complete. It was a great sight to see the frame sitting next to my cab rather than underneath it....until I found a nice big crack under the drivers side cab mount. Fortunately, I've been reassured that this is repairable. I guess I'll be "lacing some joints" as big_moss was talking about earlier, once I save up for a welder that is. With Xmas around the corner it might be a minute before I can get the coin for a nice machine. I'm thinking of the Hobart 140 gas mig machine. Anyone have experience with this one? I want to be sure it'll be strong enough for everything on this projct before I bite the bullet.
While I'm saving for the welder, I'll be making a stand on casters for the cab to sit on. That way I can move it around the garage easily. Stay tuned.....

Re: 50' GMC 5 window, my first build
 

Attachment 1470313
Don't know why I can't turn the image, just tilt head to the left haha

Re: 50' GMC 5 window, my first build
 

That's the machine I have and I like it. Good price, good service, good support.

With that being said, you have to ask yourself what you'll be using it for, after this project? I figured, projects like this are probably it. Now if i was a 4-wheeler and would start dealing with heavier gauge metal, i'd look for a bigger machine.

Good luck with whatever you choose.

Re: 50' GMC 5 window, my first build
 

Thanks iowaboy, yeah this is probably going to be the heaviest job ill tackle. I've heard a lot of good things about the Hobart 140...ill probably snatch one up. Do you know Stoner Speedshop in Hudson?

Re: 50' GMC 5 window, my first build
 

No, unfortunately I don't. I didn't start really digging into cars until i moved out here to Cali, so i'm not familiar with any of the speed shops back in the homeland.