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Author Topic: New Member with 1978 K20  (Read 8070 times)

Offline DirtyLittleSecret

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New Member with 1978 K20
« on: July 29, 2007, 06:29:28 pm »
Cheers to all on the board...
My wife was recently gifted her father's (original owner) 78 Chevy 7500lb rated K20, and I was wondering whether there's anything I ought to know specific to this rig?  We will be using it for towing/occasionally loaded with about 2000lbs.  I know lift and tyres and towing dont go hand in hand, but where its going it needs the additional ground clearance.
Its got a new 8.5:1 crate 350, 4 spd, NP205, Dana 44HD, and C14.
Thus far we've done some work: new Centerforce clutch, door panels, JC Whitney seat cover, carpet, visors, cd player, 4" Pro Comp Lift, 33" BFG MT KM's, SS brake lines, toolbox, class 4 tow hitch, fuel/breather lines, K&N, full tune up, all oils converted to synthetics, etc...
Any assistance/ideas would be appreciated!
Good to find this board!
« Last Edit: August 12, 2007, 11:59:04 pm by DirtyLittleSecret »
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78 K20: fresh 350, SM465, NP205, 4" Pro Comp, & working hard!
65 Jeep J300: 13.5:1 383, TH400, NP205, mostly NOS. 
88 Toylet LandCruiser FJ62: LT1, 4L60e, 3" OME, Aussies.
06 VW TDi: DD@72mpg.

Offline VileZambonie

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Re: New Member with 1978 K20
« Reply #1 on: July 29, 2007, 08:18:46 pm »
Welcome. What you need to know about your rig is you'll always be working on it. Good luck with it and just go through everything thoroughly
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Offline Lt.Del

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Re: New Member with 1978 K20
« Reply #2 on: July 29, 2007, 08:57:46 pm »
Hey DLS, welcome.  Are you from the other side of the big Atlantic pond?
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Offline DirtyLittleSecret

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Re: New Member with 1978 K20
« Reply #3 on: July 29, 2007, 10:56:55 pm »
Thanks for the welcome.  I grew up in numerous places: Osage Nation, Wales UK, and Hood River Oregon. 
Wanted to know if there was a particular "weak link" with this drive combination that I ought to know of...Seems like everything's properly stout, and am fortunately quite familiar with the 350.
Are there any good resources that you could recommend?  Ive found JC Whitney, Summit, and  .  Seems these classics are getting more and more difficult to find parts for...
Thanks!
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78 K20: fresh 350, SM465, NP205, 4" Pro Comp, & working hard!
65 Jeep J300: 13.5:1 383, TH400, NP205, mostly NOS. 
88 Toylet LandCruiser FJ62: LT1, 4L60e, 3" OME, Aussies.
06 VW TDi: DD@72mpg.

Offline Captkaos

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Re: New Member with 1978 K20
« Reply #4 on: July 29, 2007, 11:35:32 pm »
the site you are on right now sells serveral of the parts you just listed.  If you don't see it in the catalog, shoot us an email.  Serveral things aren't listed yet.
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Offline DirtyLittleSecret

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Re: New Member with 1978 K20
« Reply #5 on: July 30, 2007, 12:10:47 am »
Forgot to add the sister site to the forums (that's how I found the forums).  Will figure out some other goodies.  I know the Dakota Digital gauges are on my list (they've been great in my J300).
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78 K20: fresh 350, SM465, NP205, 4" Pro Comp, & working hard!
65 Jeep J300: 13.5:1 383, TH400, NP205, mostly NOS. 
88 Toylet LandCruiser FJ62: LT1, 4L60e, 3" OME, Aussies.
06 VW TDi: DD@72mpg.

Offline Prong

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Re: New Member with 1978 K20
« Reply #6 on: July 30, 2007, 01:49:22 am »
One thing to keep an eye on is the frame area around the steering gear. They love to crack around the mounting bolts.
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79 K10 SB 4x4 383/Th350
79 K10 LB 4x4 350/SM465

Offline Blazin

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Re: New Member with 1978 K20
« Reply #7 on: July 30, 2007, 05:52:25 am »
Welcome from New Hampshire.
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Offline DirtyLittleSecret

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Re: New Member with 1978 K20
« Reply #8 on: July 30, 2007, 02:30:50 pm »
Quote from: Prong on July 30, 2007, 01:49:22 am
One thing to keep an eye on is the frame area around the steering gear. They love to crack around the mounting bolts.

Is this something I ought to simply do for prevention's sake?  Also, I was noticing that there are'nt any rubber bushings between the bed and the frame...was there some sort of pad in stock form?  Lastly, does anyone here know what kind of posi Chevy used in this application?  Looks like an Auburn, but cant quite see with the HUGE gear set.  Getting it dialed in for another 250k miles.
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78 K20: fresh 350, SM465, NP205, 4" Pro Comp, & working hard!
65 Jeep J300: 13.5:1 383, TH400, NP205, mostly NOS. 
88 Toylet LandCruiser FJ62: LT1, 4L60e, 3" OME, Aussies.
06 VW TDi: DD@72mpg.

Offline Captkaos

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Re: New Member with 1978 K20
« Reply #9 on: July 30, 2007, 02:36:33 pm »
Chevy used the Eaton LSD in '78 it would be the limited slip (12bolt) in the 10bolts (82-87) it would be a gov-loc.

There were no bushing under the bed, it is bolted straight to the frame.

What size tires are on the truck?  If you plan to wheel it alot and use large 33"+ tires, I would check it and would probably brace it.
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Offline DirtyLittleSecret

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Re: New Member with 1978 K20
« Reply #10 on: July 30, 2007, 02:43:32 pm »
Quote from: Captkaos on July 30, 2007, 02:36:33 pm
Chevy used the Eaton LSD in '78 it would be the limited slip (12bolt) in the 10bolts (82-87) it would be a gov-loc.

There were no bushing under the bed, it is bolted straight to the frame.

What size tires are on the truck?  If you plan to wheel it alot and use large 33"+ tires, I would check it and would probably brace it.

Good to know that there are no bed bushings to fight with.  Will order or fab a brace system.  I dont plan to wheel it alot, but it will definitely be used as a work truck (loaded with 2000lbs in the bed).  Currently running 33x10.5 BFG MT KM's.
Its got the Corp 14 rear end, and Im assuming that it would then be the Eaton.  Also good to know!
Rebuilt the front axle last night, and am considering the rear disk brake conversion...I hate drums.
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78 K20: fresh 350, SM465, NP205, 4" Pro Comp, & working hard!
65 Jeep J300: 13.5:1 383, TH400, NP205, mostly NOS. 
88 Toylet LandCruiser FJ62: LT1, 4L60e, 3" OME, Aussies.
06 VW TDi: DD@72mpg.

Offline 1976Scottsdale

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Re: New Member with 1978 K20
« Reply #11 on: August 04, 2007, 06:44:05 pm »
JCW and most other places, possibly here as well sell a brace kit for the steering box.  Also, check your rear spring perches carefully, they gather mud and rust through easily.  I just traded my 1989 Trans Am to get back my 1976 K-20 with a 1984 front clip swap.  So, I am relearning a lot of this stuff.
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Offline 1976Scottsdale

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Re: New Member with 1978 K20
« Reply #12 on: August 08, 2007, 11:38:48 pm »
Quote from: DirtyLittleSecret on July 29, 2007, 10:56:55 pm
Thanks for the welcome.  I grew up in numerous places: Osage Nation, Wales UK, and Hood River Oregon. 
Wanted to know if there was a particular "weak link" with this drive combination that I ought to know of...Seems like everything's properly stout, and am fortunately quite familiar with the 350.
Are there any good resources that you could recommend?  Ive found JC Whitney, Summit, and  .  Seems these classics are getting more and more difficult to find parts for...
Thanks!

If there is any room for improvement upon the perfection that is the drivetrain you and I both have, it would be the need for a fifth gear for overdrive. ;D
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Offline DirtyLittleSecret

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Re: New Member with 1978 K20
« Reply #13 on: August 12, 2007, 05:51:29 pm »
Tell me about it!  Honestly, the 33" tyres actually are an improvement on the highway.  Helps with the ubber low gearing!
You will not hear me complaining too much about it though!
BTW: Silly Q: Anybody know what the 7500 GVWR K20's are actually rated to tow?
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78 K20: fresh 350, SM465, NP205, 4" Pro Comp, & working hard!
65 Jeep J300: 13.5:1 383, TH400, NP205, mostly NOS. 
88 Toylet LandCruiser FJ62: LT1, 4L60e, 3" OME, Aussies.
06 VW TDi: DD@72mpg.

Offline 1976Scottsdale

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Re: New Member with 1978 K20
« Reply #14 on: August 15, 2007, 08:31:10 am »
I dont know, but I strapped a 1977 C-10 LWB to the back of mine with a 3500lb trailer and another 5 tons of scrap truck and parts to that and drug it out of the mud... of course, I had my TH400 in there at the time, the 4 speed would have been easier.
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