Squarebody on a GMT400 frame?

[treborjm87]

I've seen a video of a K10 Body on a Tahoe Frame on U-Toob...

My frame has a lot of cracks in it... I've been thinking that since the newer is stronger I would look into putting my body onto the frame of a 2005 2WD 3/4 ton. I am currently working out the details of a sale from a friend of mine. It's a single cab. It has the 6.0 LQ9 with a 4L80e

I think that this would give me a good starting point for a SAS project.

I know that the body mounts will have to be custom made. I am pretty sure that there are some huge differences in the frames, and I am hoping that a SLIGHT body lift will take care of some of those issue.

Anyone have any experience with this swap?

Thanks in advance.

 

[Blue85]

A 2005 is GMT800. I have thought about this swap to get all the good street characteristics of the newer trucks, but if SAS is the goal, why not just get another K10 truck to build on?

 

[treborjm87]

Sentimental value on this particular truck.... It needs a new frame anyway, so if I have to swap it out, I might as well use a newer frame, if it will work.

Good call on the GMT800 info.

I decided to pass on that truck anyway. It had a lot of rust on the frame. Probably some better candidates here in Texas.

Thanks for the reply.

 

[campfire]

One thing that you may find particularly annoying is that the frame spacings are different between the square bodies and the GMT400 truck. Body lift won't cure that potential headache.

Would make a fun swap, though!

 

[treborjm87]

One thing that you may find particularly annoying is that the frame spacings are different between the square bodies and the GMT400 truck. Body lift won't cure that potential headache.

Would make a fun swap, though!

As in, the placement of the body mounts themselves? I was thinking I could cut the original body mounting tabs (Not sure what they are really called) off of the GMT400 frame and use the square body mounting tabs (or fabricate new ones) to mount the body. What I'm not completely sure of is what the spacings of the GMT400 body mounting tabs are. I have the frame dimensions for the square body.

Thanks for the reply!!!

 

[campfire]

As in, the placement of the body mounts themselves? I was thinking I could cut the original body mounting tabs (Not sure what they are really called) off of the GMT400 frame and use the square body mounting tabs (or fabricate new ones) to mount the body. What I'm not completely sure of is what the spacings of the GMT400 body mounting tabs are. I have the frame dimensions for the square body.

Thanks for the reply!!!

Distance from frame rail to frame rail (Right-to-Left) is different by several inches. It's been a while since I last measured, but the GMT400 frame rails (and their corresponding body mounts) are each about 3" further from centerline (6" overall), IIRC. So the row of body mounts on the square body will be too far inboard to line up with the frame. Spacers alone won't solve that. You will have to come up with some new mounting surfaces (prolly on the body, as the fuel tank sits inboard on those trucks).


Just my initial thoughts (and I haven't done this either). There are prolly build threads out there detailing this problem (and whatever others go with this setup)

 

[Deuling]

Honestly like said above. The widths are different. i think mostly in the front area, so maybe not a huge deal.... But i think taking your frame out, fixing it, or getting another and boxing it would be easier than building all new mounts.

 

[campfire]

Honestly like said above. The widths are different. i think mostly in the front area, so maybe not a huge deal.... But i think taking your frame out, fixing it, or getting another and boxing it would be easier than building all new mounts.

Oh...yeah. I was approaching this from a "this sounds like a fun project" standpoint. If your goal is to save the truck, using another square-body frame will probably be LOTS less work. Is your existing frame unrepairable?

 

[treborjm87]

Distance from frame rail to frame rail (Right-to-Left) is different by several inches. It's been a while since I last measured, but the GMT400 frame rails (and their corresponding body mounts) are each about 3" further from centerline (6" overall), IIRC. So the row of body mounts on the square body will be too far inboard to line up with the frame. Spacers alone won't solve that. You will have to come up with some new mounting surfaces (prolly on the body, as the fuel tank sits inboard on those trucks).

Just my initial thoughts (and I haven't done this either). There are prolly build threads out there detailing this problem (and whatever others go with this setup)

Yeah, I had been thinking about the fuel tank problem too... This U Toob video www.youtube.com/watch?v=c1wk_bOLa6s that I referenced earlier was worked with a Tahoe frame (at least according to his comments). I believe that the tank is in between the rails at the rear like the K5 Blazer, Right???

As far as my frame... I have the notorious cracks around/behind my steering box. I don't have any pics, but when I took my steering box off, the crack ran pretty much from the upper right bolt hole to the bottom left hole and is working its way to the underside of the frame. When I turn the wheel, I hear a very loud popping sound from that side. I am afraid to drive it because I worry that the steering box is going to just fall off.

The "horns" on the very front of my frame has been very abused.





I also have the typical cracks in my frame where the rear shocks bolt to the frame. I think that the frame could be repaired at the front "horns", but I am pretty concerned about the steering box mount.

As far as the spacing goes, I can't figure out in my head how I would go about changing the mounting positions on the body. With the reinforcement of the body mounts on the body, is there a way to change them without causing the body to get creased or worse?

Thanks for the ideas and thoughts as well as the cautions. This may never happen... But there seems to be a lot more GMT400/GMT800's out there. The K10 frames seem to be harder to find in my area that aren't already rusted or have the common problem areas. I've seen a couple of K5 frames, but they are the older 73-80 body styles.

Thanks again!

Treb

 

[tRustyK5]

ORD weld in frame repair kit and a few hours and your frame would be stronger than it ever was at the steering box area. This is an old, and common issue with these frames and the aftermarket responded decades ago with a good and inexpensive fix. Frame horns are cake, and the rear shock mount isn't any big deal either.

The frame is mild steel, no heat treat or hardening to worry about. Don't overthink it, grab your welder and fix it.