Greg's '71 Chevy K-20
[Specifications]
[History]
[Conversion to 3/4 Ton]
Obviously, this in about our (my) '71 Chevrolet K-20 Long-wheel-base pickup. I call it "my" truck, mainly because my Mindy doesn't like to drive it. She's been spoiled with her much newer '02 Dodge Quad-Cab 2500 LWB Cummins 4x4. Let's see now... What all can I tell you about this truck? It is a one owner vehicle, which makes it pretty unusual, even for a 10 year old truck, moreless a 33 year old truck.
Specifications
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Engine - Original Chevy 350 bottom end
- Stainless Steel valves & seats (@ 118K)
- double roller Cloyes timing chain
- 3 angle valve job
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Transmission - Saginaw-Muncie 465 4-speed
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Transfer Case - New Process 205
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Front Axle - Dana 44, open differential, 4.11:1 gearing, Factory Disc Brakes
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Rear Axle - Dana 60, open differential, 4.11:1 gearing, 12"x2½" drum brakes
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Limited Slips - Part time, when custom implement tire chains are in place, 10" long & 25lbs each (strictly off-road)
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Clutch - Centerforce
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Tires - Denman Coyote 305/85R16 10 Ply (36") w/ studs
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Wheels - Steel GM 2001 Factory dropcenter
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Shell - 1988 Brahma high roof, low door
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Air Filter - K&N 14"x4"
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Battery - Optima Blem 1200 Cold Crank Amp, "Brown Top"
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Radiator - Factory Chevy 3 core
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Paint - Factory Dark Olive w/ White
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Mirrors - LMC Truck Stainless Steel
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Security - Sturm, Ruger & Co. backuped up by custom ACD Blue Heeler w/ excessive attitude.
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Rust Layer #1 - courtesy Puget Sound Weather, Washington State (90-93)
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Rust Layer #2 - courtesy Kansas & Missouri Departments of Transportation (93-97)
It's History
(No it isn't history & won't be for a long time, but it does have some history!)
My Dad, Gary Lenderink, bought it new from Steamboat Motors in March of 1971. It started life as a K-10. I was fortunate enough to go with & pick it up with Dad. We traded our '67 Jeep CJ-5 & some cash for it. It was the dark olive green & white with the Custom Deluxe trim package, a 270 hp, 350 CID small block, a SM-465 4 speed transmission, an NP-205 transfer case, a Dana 44 front axle with factory power disc brakes, power steering, a GM Corporate 12 rear axle, & an 8' fleetside bed. It was pretty basic. The only real option it had was factory installed front tow hooks. It originally came with 6-hole 16"x5" drop center rims. I have been told repeatedly, by so-called experts, that it could not have had 16" rims unless they were 8-hole & split-rims, but it did indeed have 16" drop center rims. The factory tires were 6.50x16 bias ply mud tires. It also had a factory AM radio & a dealer installed rear Luverne step bumper.
It has stayed stock pretty much the entire 30 years we've had the truck. It has had a number of CB's which didn't last as long as the truck. It has had 2 shells & 3 campers installed on it over the years. Virtually all work done on it was done by me with the exception of a couple of tune ups. As a K-10, the outer ends of the front axle were rebuilt twice & all the brakes replaced twice. It finally got new shocks around 90K miles. Then at 133K, it got a serious drivetrain upgrade to K-20 status.
Conversion to 3/4 Ton
I finally decided to convert the Chevy to a 3/4 ton. I'd spent about 5 years lookin' off & on for a decent K20 to purchase, but none I'd seen were in remotely as good a shape as my K10. After doin' some research, I discovered that the K10s &: K20s shared the same frame. Since my truck already had the V-8 & the SM-465, only the axles & springs needed to be changed out to make it a K20. Of course this also involved changing the brake booster since the & 1/2 ton & the 3/4 ton used completely different boosters.
The Rear Axle
My first decision was to go with the Dana 60 rear axle. C20s came with either the Dana 60 or the GM Corporate (Eaton) rear axle. While the Eaton axle is far stouter than the Dana 60, it is virtually impossible to get parts for, save for some brake items. I figured Dana 60 parts would be far easier to come by so I began to look for a stock Dana 60. I discovered this was all but impossible, since it a popular unit to swap into serious 4x4s. After lookin' for some time I decided it might be easier to find a used truck w/ suitable donor axles & brake parts. I was fortunate enough to find a '72 GMC K2500 for $1500 that actually ran & had a complete snow plow. The body was a mess except the front clip, but the front axle had been recently gone thru & would need little work. The Dana 60 was a different story, but I figured it I could sell off parts from the rest of the truck to pay for the Dana 60 rebuild. The truck also had 4.11:1 gearing which was perfect for the tires I wanted to install on my Chevy. The 60 needed virtually everything replaced except for the axles themselves & the housing. This included the diff carrier because it had spun a bearing on the housing. The bearing race looked OK, but I opted to stake the housing in a few spots to make sure it didn't move again. I also had a concern that the housing may have spread some, resulting from the spun bearing or possibly causin' the spun bearing. When I setup the new ring & pinion, I was unable to get an optimal wear pattern for both longevity & strength, but did get it set up for maximum strength. I'm wasn't concerned with the rear end lasting a long time, mileage-wise because it sees less than 3K miles per year.
Just for reference, no parts store will list a '71 Chevy K20 (nor '72) as having a Dana 60 axle & I not real sure why. I've worked on a lot of these trucks over the years & the parts manuals have most of the rear axle parts listed incorrectly for the 4x4. This truck has 12"x2½" rear drums. The books all say it has 12"x2" drums or 13"x3" (Eaton axle). The axle in the books that list this axle correctly is listed as bein' in a C20 (2WD) or G20 (stepvan). Go figure!