New Guy- K20 vs. K10 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Growdon · 12-28-2002, 09:51 AM

I am new to this board. I have been a fan of these rigs since I was a little kid. I owned a 72 K5 CST up until about a month ago. It hurts , but I needed to get something more practical and needed a little cash. I am looking to build a flat bed 4X4 with a mild lift, heavy drivetrain (14bolt/Dana 60?) and 35's or their metric equivalent for higher ply tiers. My question is basically what is the difference between a 3/4 ton and a 1/2 ton (K10-K20)? Is there any difference in the frames? What axles do the K20's usually come with from the factory (1971-1972) I know that I am looking for a truck with an NP205, but what 4 speeds came in these trucks, and should I be looking for a certain tranny (my blazer had a TH350).

I have 4 trucks I am going to go look at on Sunday three K20's and one K10.

Thank you.

*Gee_Emm* · 12-28-2002, 10:23 AM

The cab mounts are different between 1/2 tons and 3/4 tons in 2 wheel drive. I don't know about the 4x4 stuff.

da-burb · 12-28-2002, 10:34 AM

Welcome to the best thing on the web!

Here's what I know about your questions. The rear axle in a 3/4 ton 4x4 will be a Corporate/Eaton Rearend. It is plenty strong, but some parts can be scarce. The front axle will be a Dana 44. On a half ton you get a 12 bolt in the back and the same Dana 44 in the front.

If you are looking at 71-72's only. You will have front disc brakes. 1970's will be front drum, but easily changed over to disc. 1969 and older will have the enclosed knuckle and you would have to swap the entire axle out to get disc brakes.(not difficult since you can use any axle well into the 80's)

Unless you are looking at a 6cylinder truck, the transfer case should be a NP205. There were a few Dana 20's out there.

GMC71k20 · 12-28-2002, 04:10 PM

the dana 44s on k20s are HD's, k10s have regular 44's, the 4 speed you should look for is the sm465 which most came with i tihnk.

**JIMs70GMC** · 12-28-2002, 07:00 PM

All I can add is that a few GMC 3/4 tons came with a Dana 60 in the rear. The eaton/corp rear could have a detroit locker and the rear dana60 came w/ the powr-loc. The front ends 1/2 and 3/4 came with the dana 44 and was rated for 3500 lbs for either model. The rear axle is what decided gross vehicle weight. My 70 has drums w/ open knuckles. Front springs on a stock truck will either be 2 leaf or optional 3 leaf HD. As was mentioned above the body mounts are the same for 4wd models. I think the dana20 TC only came in K5s with a straight 6 or something like that.

Vince M · 12-28-2002, 08:55 PM

I'm pretty sure the cross section of the frame on the 3/4 ton (K20) is thicker than the 1/2 ton but I don't know the dimensions off the top of my head.

Rod · 12-28-2002, 10:58 PM

Welcome from

Any 4spd you get in a 4x4 should be a sm465 in 71-72.
All trucks with 4 spds have NP205 in 71-72.
Rear end could be either Dana or Eaton/Corporate.
Posi front was an option too in these yeats but not often ordered but a few members here have it in theirs from the factory.
Power Lok in the dana rear or no-spin detroit locker in the corp diff possible too.
All the 4x4 trucks use the same body mount kits.
3/4 front diff is a heavier duty dana 44.
71-72 will have disc front brakes.
If you find an automatic trucks 4x4 it will have a turbo 350 tranny hooked to a NP 205.
Extra leaf springs is about only difference between frames of 1/2 ton to 3/4 ton 4x4.
All what I list is stock available equipment for this era truck.

**BIG ORANGE** · 12-28-2002, 11:04 PM

Welcome from the palmetto state!

70cst10_05 · 12-29-2002, 12:35 AM

i don't know squat on the technical stuff of k20's and k10s, i know that my uncles has a k20 and it rides ruffer than crap, but don't all old trucks????haha i don't know if a 1/2 ton would be any better or not, everybody probly knew that by now though.

kevin

**Yukon Jack** · 12-29-2002, 10:39 AM

Regarding the frame issue, my restoration pack shows there is a difference between the 1/2 ton and 3/4 ton frames. It's a strenght issue rather than a dimensional difference. I get the pack from my office Monday and post that info.

Growdon · 12-29-2002, 11:27 AM

Thanks for the help guys. I am going to look at some trucks this afternoon. The 1/2 ton is in good running condition and has a four speed. I don't know much about the 3/4 tons yet, but we will see. I found a 14 bolt off a 77 1 ton with 411's for $200.00, that I will probably buy and put in what ever I buy anyways. If any of the 3/4 tons have a Dana 60 it would be hard to pass up.

special70gmc · 12-29-2002, 05:23 PM

is the dana 60 with 4.10 gears stock on my camper special 3/4 ton? o yeah its a 2wd

Longhorn Man · 12-29-2002, 06:34 PM

It probabl;y is. That seems top be one of the options that doesn't always get listed...kinda like leaf/coil rear ends.

GMC71k20 · 12-29-2002, 06:51 PM

what type of rear end is this in my 3/4 ton

da-burb · 12-29-2002, 07:07 PM

That is the Corporate/Eaton. The salad bowl pumpkin is the dead give-away.

GMC71k20 · 12-29-2002, 07:09 PM

thanks, ive been wondering what it was. in the 71 GMC manual it said standard rear end for 3/4 ton was spicer 60. i never heard of it before

Growdon · 12-29-2002, 07:30 PM

I went and looked at the two 3/4 ton trucks today, I won't be able to see the 1/2 ton until tomorrow. Here's what They are.

1970 K20 with corporate dually rear axle from 1 ton or larger. The truck has a flat bed and the cab etc. is in fair condition. It has a 350/ TH350/ NP205, and Dana 44 front axle. It has power brakes and power steering. This rig is in decent.

1972 GMC 3/4 ton - Body poor to fair condition (original AC cab) Dana 44 front, Dana 60 rear. NP205/350/ TH350. NP205 is busted and out of the truck but the driveshafts are there. Doesn't run and hasn't for six years.

The guy wants $1500 for both.

I asked him about selling the GMC by itself for the axles, driveshafts, core 350, and spare glass (all good). He said $400.00. I can't pass that up.

What to do?
I guess I'll decide tomorrow after seeing the other truck.

**Yukon Jack** · 12-30-2002, 01:24 PM

About the frames, the resto pack says the K10 frame is 39,000 lb-test steel; section modulus 2.70 (KS-KE107 models); 3.48 (KS-KE109 models)

The K20 frame is also 39,000 lb-test steel, section modulus 3.48.

Regardless, I wouldn't let frame strength control my decison between a K10 and a K20 at all.

neonlarry · 12-30-2002, 05:05 PM

How did you find those??? I have been looking for one for years, and I have only seen one for less that about $3500. If you don't buy one or both of those trucks, let me know, becuase i would be very interested in one for that cheap, even if it does need a lot of stuff. I could get all of the parts to fix that GMC really easy if you don't buy it. If you come across any cheap 67-72 4x4s I really want one, so let me know.

Also, if you do like you were thinking and buy the GMC just for some of the parts, I would buy the rest of it from you too if you wanted to sell it.

ozarkhippie · 12-31-2002, 12:23 AM

Yukon can you help clear me on this: how do you determine your model no.- ex. (KS-KE109 models) And so its saying that some half to frame are the same specs as the 3/4?

ozarkhippie · 12-31-2002, 12:29 AM

I guess I answered my own question. Its talking about the model no. that is located on the glovebox door.

ozarkhippie · 12-31-2002, 12:30 AM

I guess I answered my own question. Its talking about the model no. that is located on the glovebox door. What is a resto pack? Sound like its got good info. Can they be purchased?

Growdon · 12-31-2002, 01:07 AM

NEONLARRY

I will let you know what I decide to do about the trucks. The guy with the K-10 is out of town and won't be back until tomorrow. I have information about another 1972 chevy K20 with 350, TH350, NP205. The guy says the tranny is toast and he hasn't driven it in six years. He has a second C20 with 292 etc. that isn't running. He would sell both for $2000.00. That was his original price and I think you could get them for less $. I am going to see this K20 as soon as possible. The C20 he wants to sell with it is too far away (located in a different town than the K20).

I live west of Reno about an hour. Total hick farmland area. That is why they've been so easy to find. I'll try to take some digital photo's of the rigs I am looking at so I can show you the ones I don't choose to buy.

12-28-2002, 09:51 AM	#1
Growdon Registered User Join Date: Dec 2002 Location: Northern California Posts: 53	New Guy- K20 vs. K10 I am new to this board. I have been a fan of these rigs since I was a little kid. I owned a 72 K5 CST up until about a month ago. It hurts , but I needed to get something more practical and needed a little cash. I am looking to build a flat bed 4X4 with a mild lift, heavy drivetrain (14bolt/Dana 60?) and 35's or their metric equivalent for higher ply tiers. My question is basically what is the difference between a 3/4 ton and a 1/2 ton (K10-K20)? Is there any difference in the frames? What axles do the K20's usually come with from the factory (1971-1972) I know that I am looking for a truck with an NP205, but what 4 speeds came in these trucks, and should I be looking for a certain tranny (my blazer had a TH350). I have 4 trucks I am going to go look at on Sunday three K20's and one K10. Thank you.

12-28-2002, 10:34 AM	#3
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	Welcome to the best thing on the web! Here's what I know about your questions. The rear axle in a 3/4 ton 4x4 will be a Corporate/Eaton Rearend. It is plenty strong, but some parts can be scarce. The front axle will be a Dana 44. On a half ton you get a 12 bolt in the back and the same Dana 44 in the front. If you are looking at 71-72's only. You will have front disc brakes. 1970's will be front drum, but easily changed over to disc. 1969 and older will have the enclosed knuckle and you would have to swap the entire axle out to get disc brakes.(not difficult since you can use any axle well into the 80's) Unless you are looking at a 6cylinder truck, the transfer case should be a NP205. There were a few Dana 20's out there. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

12-28-2002, 07:00 PM	#5
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	All I can add is that a few GMC 3/4 tons came with a Dana 60 in the rear. The eaton/corp rear could have a detroit locker and the rear dana60 came w/ the powr-loc. The front ends 1/2 and 3/4 came with the dana 44 and was rated for 3500 lbs for either model. The rear axle is what decided gross vehicle weight. My 70 has drums w/ open knuckles. Front springs on a stock truck will either be 2 leaf or optional 3 leaf HD. As was mentioned above the body mounts are the same for 4wd models. I think the dana20 TC only came in K5s with a straight 6 or something like that. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

12-28-2002, 08:55 PM	#6
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	I'm pretty sure the cross section of the frame on the 3/4 ton (K20) is thicker than the 1/2 ton but I don't know the dimensions off the top of my head. __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.

12-28-2002, 10:58 PM	#7
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Welcome from Any 4spd you get in a 4x4 should be a sm465 in 71-72. All trucks with 4 spds have NP205 in 71-72. Rear end could be either Dana or Eaton/Corporate. Posi front was an option too in these yeats but not often ordered but a few members here have it in theirs from the factory. Power Lok in the dana rear or no-spin detroit locker in the corp diff possible too. All the 4x4 trucks use the same body mount kits. 3/4 front diff is a heavier duty dana 44. 71-72 will have disc front brakes. If you find an automatic trucks 4x4 it will have a turbo 350 tranny hooked to a NP 205. Extra leaf springs is about only difference between frames of 1/2 ton to 3/4 ton 4x4. All what I list is stock available equipment for this era truck. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

12-28-2002, 10:23 AM	#2
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 3,991	The cab mounts are different between 1/2 tons and 3/4 tons in 2 wheel drive. I don't know about the 4x4 stuff.

12-28-2002, 04:10 PM	#4
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	the dana 44s on k20s are HD's, k10s have regular 44's, the 4 speed you should look for is the sm465 which most came with i tihnk.

12-28-2002, 11:04 PM	#8
BIG ORANGE Senior Member Join Date: Oct 2001 Location: Lancaster S.C. Posts: 4,764	Welcome from the palmetto state! __________________ Things happen for a reason!

12-29-2002, 12:35 AM	#9
70cst10_05 Registered User Join Date: Dec 2002 Location: Summerfield, Ks Posts: 741	i don't know squat on the technical stuff of k20's and k10s, i know that my uncles has a k20 and it rides ruffer than crap, but don't all old trucks????haha i don't know if a 1/2 ton would be any better or not, everybody probly knew that by now though. kevin

12-29-2002, 10:39 AM	#10
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	Regarding the frame issue, my restoration pack shows there is a difference between the 1/2 ton and 3/4 ton frames. It's a strenght issue rather than a dimensional difference. I get the pack from my office Monday and post that info. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

12-29-2002, 11:27 AM	#11
Growdon Registered User Join Date: Dec 2002 Location: Northern California Posts: 53	Thanks for the help guys. I am going to look at some trucks this afternoon. The 1/2 ton is in good running condition and has a four speed. I don't know much about the 3/4 tons yet, but we will see. I found a 14 bolt off a 77 1 ton with 411's for $200.00, that I will probably buy and put in what ever I buy anyways. If any of the 3/4 tons have a Dana 60 it would be hard to pass up.

12-29-2002, 05:23 PM	#12
special70gmc Registered User Join Date: Sep 2002 Location: long island, new york Posts: 1,333	is the dana 60 with 4.10 gears stock on my camper special 3/4 ton? o yeah its a 2wd __________________ 1986 c-10 swb 5/7 drop 20'' coys 1958 belair 2door

12-29-2002, 06:34 PM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	It probabl;y is. That seems top be one of the options that doesn't always get listed...kinda like leaf/coil rear ends.

12-29-2002, 06:51 PM	#14
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	what type of rear end is this in my 3/4 ton Attached Images

12-29-2002, 07:07 PM	#15
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	That is the Corporate/Eaton. The salad bowl pumpkin is the dead give-away. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087



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12-29-2002, 07:09 PM	#16
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	thanks, ive been wondering what it was. in the 71 GMC manual it said standard rear end for 3/4 ton was spicer 60. i never heard of it before

12-29-2002, 07:30 PM	#17
Growdon Registered User Join Date: Dec 2002 Location: Northern California Posts: 53	follow-up I went and looked at the two 3/4 ton trucks today, I won't be able to see the 1/2 ton until tomorrow. Here's what They are. 1970 K20 with corporate dually rear axle from 1 ton or larger. The truck has a flat bed and the cab etc. is in fair condition. It has a 350/ TH350/ NP205, and Dana 44 front axle. It has power brakes and power steering. This rig is in decent. 1972 GMC 3/4 ton - Body poor to fair condition (original AC cab) Dana 44 front, Dana 60 rear. NP205/350/ TH350. NP205 is busted and out of the truck but the driveshafts are there. Doesn't run and hasn't for six years. The guy wants $1500 for both. I asked him about selling the GMC by itself for the axles, driveshafts, core 350, and spare glass (all good). He said $400.00. I can't pass that up. What to do? I guess I'll decide tomorrow after seeing the other truck.

12-30-2002, 01:24 PM	#18
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	About the frames, the resto pack says the K10 frame is 39,000 lb-test steel; section modulus 2.70 (KS-KE107 models); 3.48 (KS-KE109 models) The K20 frame is also 39,000 lb-test steel, section modulus 3.48. Regardless, I wouldn't let frame strength control my decison between a K10 and a K20 at all. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

12-30-2002, 05:05 PM	#19
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,745	How did you find those??? I have been looking for one for years, and I have only seen one for less that about $3500. If you don't buy one or both of those trucks, let me know, becuase i would be very interested in one for that cheap, even if it does need a lot of stuff. I could get all of the parts to fix that GMC really easy if you don't buy it. If you come across any cheap 67-72 4x4s I really want one, so let me know. Also, if you do like you were thinking and buy the GMC just for some of the parts, I would buy the rest of it from you too if you wanted to sell it. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

12-31-2002, 12:23 AM	#20
ozarkhippie Registered User Join Date: Nov 2002 Location: Eureka Springs AR Posts: 494	Yukon can you help clear me on this: how do you determine your model no.- ex. (KS-KE109 models) And so its saying that some half to frame are the same specs as the 3/4? __________________ Buy Sale or Trade 71 3/4 4x4 72 1/2 ton cheyenne 4x4

12-31-2002, 12:29 AM	#21
ozarkhippie Registered User Join Date: Nov 2002 Location: Eureka Springs AR Posts: 494	I guess I answered my own question. Its talking about the model no. that is located on the glovebox door. __________________ Buy Sale or Trade 71 3/4 4x4 72 1/2 ton cheyenne 4x4

12-31-2002, 12:30 AM	#22
ozarkhippie Registered User Join Date: Nov 2002 Location: Eureka Springs AR Posts: 494	I guess I answered my own question. Its talking about the model no. that is located on the glovebox door. What is a resto pack? Sound like its got good info. Can they be purchased? __________________ Buy Sale or Trade 71 3/4 4x4 72 1/2 ton cheyenne 4x4

12-31-2002, 01:07 AM	#23
Growdon Registered User Join Date: Dec 2002 Location: Northern California Posts: 53	NEONLARRY I will let you know what I decide to do about the trucks. The guy with the K-10 is out of town and won't be back until tomorrow. I have information about another 1972 chevy K20 with 350, TH350, NP205. The guy says the tranny is toast and he hasn't driven it in six years. He has a second C20 with 292 etc. that isn't running. He would sell both for $2000.00. That was his original price and I think you could get them for less $. I am going to see this K20 as soon as possible. The C20 he wants to sell with it is too far away (located in a different town than the K20). I live west of Reno about an hour. Total hick farmland area. That is why they've been so easy to find. I'll try to take some digital photo's of the rigs I am looking at so I can show you the ones I don't choose to buy.

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