1/2 ton - 3/4 ton frames??

[Scott>72-GMC]

Screwed up on my first post title. What is the diffrence in the frames from 1/2 ton to 3/4 ton truck. I have both and both are 1972
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[RHGuyettejr]

If it is going from a leaf spring to leaf spring application, or IFS-IFS they should be the same and just the springs change.... if you are going from say a 2wd rear leaf spring setup to trailing arm I believe the trailing arm frames are narrower in the rear? Don't quote me on that though. typically 3/4 tons will sit a little higher because of the leaf packs. This is also assuming you are going 2wd-2wd or 4wd-4wd.

[Scott>72-GMC]

They are both 2wd the 3/4 ton is trailing arm haven't looked at the 1/2 ton the 3/4 Ton is out of state didn't know if I could be pro active and get this frame ready off the half or if switching would be more of a waist of time
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[RHGuyettejr]

Well regardless if you are just swapping bodies, and use the suspension and entire undercarriage from whatever truck you want the frame from, the body should bolt to the other frame. Issues you may have are If its a high hump or low hump floor pan, but that's a relatively easy fix. Im currently swapping a 69 gmc 3/4 ton to a 71 Chevy 3/4 ton 4x4. I'm just putting the 69 body on the 4x4 truck frame. Everything bolts up the same, its just the axles and suspension that will change.
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[Scott>72-GMC]

I'm pretty sure they have the same humps just didn't know if the frame on the 3/4 ton were more stout or stiffened some how
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[RHGuyettejr]

To my knowledge the 20 series frames are no stronger than the 10 series frames, but they can handle more weight because of suspension and axle upgrades.
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[Mustard72]

I'm no expert, but I believe the only trucks that would have the high hump would be 4x4 or big block trucks.

[Scott>72-GMC]

Right on thanks for the help
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[toyplumbertrucks]

Here is something to think about. The 3/4 ton brake parts and wheels and tires cost alot more when you have to change them. You also have alot more options with the 1/2 ton suspenison than you do the 3/4. I actually went with the 3/4 ton 4x4 frame and suspension, but if I was to do it again I think I would stick to a 1/2 ton 2wd, alot cheapier to build and alot smoother to ride in, and easier to find parts.

[Scott>72-GMC]

I just see myself using my truck for some heavy applications maybe a fith wheel and such the main reason I want the 3/4 ton. Maybe wood haulin. Luckily I bought it with brand new rubber and new exhaust but I know what you mean when it comes to tires can't be as much as the new trucks with there 17s plus I'm a quadriplegic so it won't be driven a ton I apriciate all input though. A lot.
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[SS Tim]

They are not the same.

Here are the frame section and modulus numbers, 39k psi carbon steel through C30s. Note the increased section height, flange width and thickness changes of the frame as the series step up.

C Blazer
C10 115
C10 127 6.04" height 2.53" flange width 0.156" thick 2.98 section modulus

C20 127 6.11" height 2.46" flange width 0.194" thick 3.71 section modulus

C20/30 133 (Longhorns) 7.20" height 2.77" flange width 0.194" thick 5.05 section modulus

C30 157 8.18" height 2.97" flange width 0.224" thick 7.29 section modulus


K Blazer
K10 115 6.02" height 2.71" flange width 0.141" thick 2.70 section modulus

K10 127
K20 127 6.09" height 2.75" flange width 0.186" thick 3.48 section modulus

[Boog]

I knew they were different but couldn't find my info right away. Thanks for adding that Tim.
Some say the 3/4 ton trailing arms have additional metal for strength too.

[Scott>72-GMC]

Thanks. Ill stick with the 3/4 frame being from Colorado desert it has less rust anyway. I knew they had to be beefed up some how yet I know 1/2 tons can handle alot more then they are rated for
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[capev86]

vs a 1/2 ton, my 72 Burb 3/4 ton has:

a bigger brake booster
extra plate welded on trailing arms
thicker (larger diameter) track bar
larger rear brakes

wheel choices don't bother me as i prefer a more factory looking truck and the heavy duty parts make for peace of mind when trailer towing.

[Scott>72-GMC]

Very true. My truck came with some aftermarket aluminum rims other than that its stock I believe
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