1971 k30 LS3 500hp 4l80e, 205, Dana 70f, 14bff,

[Cobalt964ruf]

1971 k30 build. Truck is a c10 and being built into a k30. Background, I'm a ase master gm tech, ase master porsche tech, and also own a private machine shop with small foundry capabilities. So wrenching and fabrication are not new to me. Truck is a complete c10 super Cheyenne. It has seen better days, it needs both cab corners, both rockers. It's a good candidate for this build. I will post the original running gear for sale in the classifieds section.

[Cobalt964ruf]

The build: ls3 crate motor with hotcam kit. stage 4 4l80e transmission. np205 rebuild with new bearings, gaskets, and seals. 1480 outputs. 1985 Dana 70 front axle, being rebuilt with all new spicer bearings, spicer seals, spicer kingpins upper and lowers. New Detroit locker with new warn 35 spline lockout hubs. 4.10 Yukon gears. 1985 14bolt full float p30 g80 rear axle. Rebuild with new bearings, new seals and gaskets. 4.10 Yukon gears new Detroit locker. Rear disc brake conversion. So far I have the truck and all the major parts so let's get started.

[Cobalt964ruf]

[yuccales]

Lot of good parts going into your rig. Keep the pics coming as you build.

[Cobalt964ruf]

almost forgot the important part... will be painted medium blue with white cab roof and white center stripe on sides. 6" skyjacker lift all springs, no blocks with shocks and stainless braided brake hoses. 1985 1ton hydroboost and master cylinder setup. new 35" bfg all terrain tires on vintage fairly correct looking 8 lug alloy 16x8 wheels.

[Cobalt964ruf]

donor truck, 47k miles 1985 1ton 4x4 srw those are the tires and wheels too.

[chev3600]

That's about as far from a RUF 964 as you can get! Looks like its gonna be a cool project though.

[Cobalt964ruf]

Ya, my car is a ruf 964. But love these old trucks too.

[Tom Vogel]

What are you going to do to upgrade the frame?

[Cobalt964ruf]

I'm completely boxing the frame with 3/16" plate. Will also be reinforcing the structural points. Ladder framing with 3"x6" .250 rectangle to replace front and rear frame crossmembers.

[ERASER5]

Getting the pop corn ready...

[Iron Hauler]

What's the Dana 70 front axle out of?

[Cobalt964ruf]

Dana 70 is from 1985 M1031 military 1.25ton truck

[Cobalt964ruf]

The donor truck is a ex Air Force/military m1031 1.25ton 4x4 crew cab. 6.2 diesel, th400, np205, dana 70f, 14bolt full float rear in stock form. i am not using the motor or trans from donor truck. It was dessert sand/tan originally and someone painted it blue as seen in the pic above. The roof is still tan if you look at the pic closely.

[SS Tim]

You are aware that 67-72 LWB CK 10-20 trucks had a 127" wheelbase and that the factory C30s had 133" as pickups? That is one of the features of the Longhorns the forward extended 8-1/2' bed due to the longer frame.

It wasn't until the 73 MY change that all the LWB (single cab) trucks went to a common standard 131.5" wheelbase and the 8-1/2 and 9' pickup beds went away.

From the list you have it sounds like your truck is going to weigh close to max GVW on the original data plate empty!

Also here is a breakdown of the various frames from 67-72.

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" section height, 2.53" flange width, 0.156" thick, 2.98 section modulus

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

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

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


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

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

[Cobalt964ruf]

Thank you SS Tim for the info. I will be boxing in the frame completely, and replacing the front and rear structural crossmembers with 3"x6" .250 rectangle. Should make the frame stupid strong.

[Cobalt964ruf]

I will be using the c10 frame not the crew can frame

[Iron Hauler]

That should make for a very strong drivetrain. I've worked on a few of the GM M series military trucks and they all had Dana 60 fronts, I didn't know GM ever used a Dana 70 front.

[Cobalt964ruf]

Very few had 70's. but the m1031 was the most HD they had in pu form. Some m1031's were dually's and some were srw. I don't know if all m1031's had 70's but this one does.

[Cobalt964ruf]

I have seen other discrepancies in the military chevrolet trucks too. When I was searching for a donor truck some had 208 tcases and some had 205's. this one has a 205. All m1008's and m1028's have dana 60f's tho, so you are for the most part correct. The m1031 has front and rear gov loc's too. But I'm replacing those with true Detroit lockers front and rear.

[Vintage Windmills]

Hi, Sounds like a fun project and you have the tools to do the job. The crew cab looks too nice to part? Since you're just using the axles, wonder if you could swap a Dana 60 under there and keep it as a complete truck to get your money back? Also, you may want to look for an H052 since your doing a rear disc conversion anyways. Compared to a 14 bolt, the HO52 is stronger, lighter, more ground clearance, and can be found (if lucky) with a factory installed detroit locker. You can also pull the 3rd member and leave the axle in the truck. I see the 14 bolt as a cost reduction only on GM"s part. The HO52 is basically a smaller version of a Eaton dump truck rear end. Its just wasn't popular becuase of brake parts availability but that is now managed with the same disc brake conversion plates as a 14 bolt.

Also, you may want to be careful with the mismatch in strength between rectangular tube 1/4" thick wall and the c10 frame. You'll want things to "share flexing" and not have a sudden change in stiffness otherwise cracks can happen.

Nice find on the D70!

[Cobalt964ruf]

Thank you for your kind words and encouragement.

[special-K]

That's a great plan. The frame is strong enough,unless you plan on crazy big loads. I build stuff like this and what I do depends on what way I'm going. I've done 67-72 K/30s (that's what I call any truck with 1t axles) as beefy work trucks,off road with the right stuff,to looks like factory did it. Lots of K/30s (especially SRW) from day one were bought for the heavier axles and not the added GVW.
I don't know of any Dana 70 front axles*,only Dana 60s. That model got Tru-Trac up front and NP205s. Why do you need two donor trucks?

*...on these CUCVs

[Cobalt964ruf]

Thank you all. It is a dana70. No debates needed. Moving on in a positive manner. Ordered today; the np205 rebuild kit, the griffin 3 core aluminum radiator, the 20 gal aluminum fuel cell, complete spicer rebuild kit for the 70, timken rebuild kit for the 14bff, a pair of stainless flow masters, and some new body emblems.

[Cobalt964ruf]

my 14bff rear disc brake kit I built. milled and cross drilled parts in my private machine shop.