Revisiting K10 vs K20 vs K30 frame specs.

[Kapdin]

Hello Gents! Its been a while since I've posted anything but this topic has been eating at me for a long time and since I could not Google a exact answer (contradicting answers every page I found), I assume others would like to hear what I have found. I also apologize if this has been answered but I have not seen it. I also apologize if my train of thought isn't very smooth but bear with me here.

I am just going to start with my answers and than try to show and explain.

1st
*73-79 K10 & K20 frames are IDENTICAL.

2nd
*73-79 K10 & K20 frames are "slightly" thicker than 80's K10 & K20 std. frames.

3rd
*73-79 K10, K20 & K30 (single cab and crew cabs) frames are the SAME thickness. (K30's are BIGGER frames but I am just talking "Thickness")

4th
*80-87 K30 crew cab's are the thickest frames among our squares.

5th
*80-87 K20's with RPO code C6P have the same frame thickness as 80-87 crew cabs. C6P aka. HD package or I believe "camper specials".

6th
*Based on RBM (Resisting bending moment) all our frames use the same grade steal (tensile strength).

Here is the website I found my charts from.

https://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html

If you go under "Chevrolet Trucks (All Models Not Listed Below)" and search through ALL 73-87 manuals you will notice the C6P specs DO NOT start till you get into the 1980 manual.

1979 GM MANUAL! Notice no C6P option.

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1980 GM MANUAL! Notice the C6P option.

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Next here is the Frame Specs chart I pulled from the same 1979 manual.

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Here are my thoughts in RED.

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Next I found the same type of chart in a 1987 manual. (they do not have this chart in every year's manual WTF?

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Now my thoughts on that chart.

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Now after I deciphered these charts I had to find PHYSICAL proof of my findings. I found my proof of the C6P RPO code on
http://www.rustfreeclassics.com/sold_vehicle_archive.htm
and just search through all the 3/4 tons because he has taken a photo of every RPO code chart of these. None of the 70's have the C6P code listed on any of them (could be chance). But if you look at most of his 80's 3/4 tons (which if I remember I found he had a 85-87 with the C6P code).

So what does this all mean? Well...... 73-79 K10 & K20's have slightly stronger frames than 80's std. K10 & K20's frames. All though 80's offered a 3/4 ton frame as thick as their K30's crew cabs had. I also noticed that 73-79 K30 crew cabs had thinner frames than 80-87 crew cabs had (WEIRD! ). Also..... why is the Single cab K30 in the 80's THINNER than the K30's crew cabs and in turn the C6P K20's??????

Anyways PLEASE correct me with PROOF but as far as I can research this all holds true.

 

[marks86]

awesome write up, Id say this needs to be saved somewhere so we can all see this

 

[da_raabi]

Sticky Sticky Sticky!!!

 

[marks86]

Sticky Sticky Sticky!!!

to far?

 

[nvrenuf]

Good info. You should include '88-'91 R & V series trucks.

 

[MadOgre]

I guess your not really gonna notice the difference from the c6p to regular with your eye?

I have a 6.2 diesel k10 and an 87 HD k20 and they look exactly the same with my eyes.

 

[da_raabi]

I guess your not really gonna notice the difference from the c6p to regular with your eye?

I have a 6.2 diesel k10 and an 87 HD k20 and they look exactly the same with my eyes.

Probably not. Its a nominal difference. You are talking a difference of .03" thickness. I don't know what that equates to in overall strength but it sure don't seem like much to me. I'd like to meet the guy that could see that just by looking!

 

[NCBurb]

FWIW my 87 Suburban V20 has C6P code, which makes sense for this theory...

 

[Brando Marlin]

Hello Gents! Its been a while since I've posted anything but this topic has been eating at me for a long time and since I could not Google a exact answer (contradicting answers every page I found), I assume others would like to hear what I have found. I also apologize if this has been answered but I have not seen it. I also apologize if my train of thought isn't very smooth but bear with me here.

I am just going to start with my answers and than try to show and explain.

1st
*73-79 K10 & K20 frames are IDENTICAL.

2nd
*73-79 K10 & K20 frames are "slightly" thicker than 80's K10 & K20 std. frames.

3rd
*73-79 K10, K20 & K30 (single cab and crew cabs) frames are the SAME thickness. (K30's are BIGGER frames but I am just talking "Thickness")

4th
*80-87 K30 crew cab's are the thickest frames among our squares.

5th
*80-87 K20's with RPO code C6P have the same frame thickness as 80-87 crew cabs. C6P aka. HD package or I believe "camper specials".

6th
*Based on RBM (Resisting bending moment) all our frames use the same grade steal (tensile strength).

Here is the website I found my charts from.

https://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html

If you go under "Chevrolet Trucks (All Models Not Listed Below)" and search through ALL 73-87 manuals you will notice the C6P specs DO NOT start till you get into the 1980 manual.

1979 GM MANUAL! Notice no C6P option.

You must be registered for see images attach

1980 GM MANUAL! Notice the C6P option.

You must be registered for see images attach

Next here is the Frame Specs chart I pulled from the same 1979 manual.

You must be registered for see images attach

Here are my thoughts in RED.

You must be registered for see images attach

Next I found the same type of chart in a 1987 manual. (they do not have this chart in every year's manual WTF?

You must be registered for see images attach

Now my thoughts on that chart.

You must be registered for see images attach

Now after I deciphered these charts I had to find PHYSICAL proof of my findings. I found my proof of the C6P RPO code on
http://www.rustfreeclassics.com/sold_vehicle_archive.htm
and just search through all the 3/4 tons because he has taken a photo of every RPO code chart of these. None of the 70's have the C6P code listed on any of them (could be chance). But if you look at most of his 80's 3/4 tons (which if I remember I found he had a 85-87 with the C6P code).

So what does this all mean? Well...... 73-79 K10 & K20's have slightly stronger frames than 80's std. K10 & K20's frames. All though 80's offered a 3/4 ton frame as thick as their K30's crew cabs had. I also noticed that 73-79 K30 crew cabs had thinner frames than 80-87 crew cabs had (WEIRD! ). Also..... why is the Single cab K30 in the 80's THINNER than the K30's crew cabs and in turn the C6P K20's??????

Anyways PLEASE correct me with PROOF but as far as I can research this all holds true.

 

[Brando Marlin]

Im new to the site and had a couple questions. I bought a 1987 v30 I believe. My plan was to convert it back to a stock bed and restore it but noticed the frame was longer then a normal 8ft bed. Does anyone know what i have here? Is it a cab and chassis? I know it has been extended some on the rear of the frame for the bed. Thanks!

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[Frankenchevy]

Im new to the site and had a couple questions. I bought a 1987 v30 I believe. My plan was to convert it back to a stock bed and restore it but noticed the frame was longer then a normal 8ft bed. Does anyone know what i have here? Is it a cab and chassis? I know it has been extended some on the rear of the frame for the bed. Thanks!

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Probably a CC. The wheelbase looks longer than a standard longbed.

 

[dvdswan]

Probably a CC. The wheelbase looks longer than a standard longbed.

It could have been just sold as a cab/chassis setup too. But the frame definitely is low and long behind the cab for a CC.

 

[Craig 85]

Probably a chassis cab set similar to the set up in photo #1. This truck has an 11' long bed. Are the inner duals on your truck right up against the spring pack or does it line up with the front tire? If it doesn't line up, it's definitely a chassis cab and has the narrower 14 bolt rear end.

Photo #2 is what a narrowed chassis cab rear end looks like with a standard bed. This one's 4WD, so there is no interference with the inner wheel well.

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[Bextreme04]

I'll just add a few corrections to this thread since it is back to life. The initial post should read 73-80 and 81-above. My 1980 shared the 73-80 front end, bumper, and frame style.

It should also be pointed out that while the 1980 vehicle information kit shows a C6P option, it does not show a different frame modulus for that option. It does show different power pack, suspension, and brake options. My 1980 K25 does not show a C6P RPO, but is an 8600 GVW and has all of the spring, axle, and brake components that would have been standard with a C6P option.

It seems like maybe the standard frames got thinner and weaker in 81 and later models. The C6P option in 81 and later models included a thicker frame.

 

[Luke Courtney]

Hey guys, I’m new to the forum. Very interesting so far. I have a 1988 K30 3+3 crew cab I’m shortening to a short bed. I have looked and looked and looked for specs on how much to cut off. I cannot find anything except one guy saying I should cut off 14” right behind the cab. Do you guys have any idea or can you point me in the right direction?