1965 gmc 4000

[Captainfab]

What is it about your '73 that it isn't street legal?

Originally Posted by kenbob87

haha no reason to back down... honestly i didnt think that this truck would attract this much attention lol... i am really excited to start collecting parts for this one and getting it back on the road. as soon as i get my 73 done i am going to start work on this one i just have some body work and paint to do on my 73 then it finally done! its too bad MN laws will not allow me to drive it on the street anymore lol

[kenbob87]

What is it about your '73 that it isn't street legal?

legal bumper hieght in MN is 25 inches- mine are at 39 in the front and 41 in the rear
bumpers must be bolted on mine are welded
exhaust is WAY too loud 3 inch duals off the headers then 90's up into the box then 90's over to each side of the box then 90's up again into 4 inch tips
no factory seat belts only 5 point harness's
tires stick out of the fenders roughly 5 inches legal is 1 inch
i run fully hydraulic steering there is no mechanical linkage
head lights and tail lights are to also too high

needless to say if i drove it on the road and got caught i would never see my truck again i would have some major fines to pay and probably a little jail time lol

[63burban4x4]

I'm no expert, but if I recall correctly, lots of big 4x4 conversions were done by Marmon Herrington, epecially big dump trucks for off road, and utility trucks. I'm not sure if Napco did the large trucks?
They are still around today, you may be able to find out if they made this conversion......www.Marmon-Herrington.com
I don't know if they used stock transfer cases, or something different?

[63burban4x4]

It seems to me that the size of this truck is unusual....heavier than a C-30 but lighter than a C-50 or C-60? I don't really recall a C-40 size, was this 4000 GMC rare?
It's interesting that the truck seems to have the lower, lighter cab (no running board step) but has the flared big truck fenders. I can't tell if it has a large grille shell, like say a C-60 would have...........the bigger trucks were taller in the front sheetmetal somehow, maybe a raised radiator support. I wonder if the company who did the conversion could have changed out the fenders? (I'd say it's pretty likely that a truck like this went straight from the factory to a driveline vendor then to a dealer,or even straight to a fleet) Do you suppose they shipped out of the factory without any axles at all?

[1963c-10]

There was a c-40. As for the bed work...have you considered finding a long bed step side instead of lengthening a short bed. The long beds came in 8 & 9 foot length. Pics are a 1961 c-40 and a 62 c-40 emblem

[padresag]

Originally Posted by Woogeroo

Napco's from the factory for GM ended in the 1959 model year.

All 4x4 stuff was stuff that GM built or sourced from 1960 model year and onwards.

Ya'll can geek out on details if you are interested:

Napco owner's Group

-W

gm only did inhouse 4 x 4 starting in 1960 in 1/2 & 3/4t trucks. 1t and over were Napco
ron

[63burban4x4]

the 40 series shown above has the fenders for the smaller truck, (no flare,) and no running board. also the grille shell looks shorter height, and the cab's mounted lower. so was the GMC 4000 not the same series truck as the Chevy C-40? Or, is that truck something larger than a 40? Vin# would probably answer that. Is the truck pictured here a Chevy for sure? it does have a GMC hood. (On second look at the 4x4 truck, it does look like there may have been a running board, just missing.)
I looked at a C-60 recently, and the cab, though the same as the 10-30's is mounted higher, and has a flat floor with no trans hump. it also had a "taller" grille shell.

I remember years ago (1970's) attending an auction at a utility line construction company that was closing up. They had acres of big series all-wheel-drive trucks outfitted for off road line work, and most of it was Marmon-Herrington conversions, we actually bought a couple of them. They weren't Chevys, though. one was a Ford, and one was a corn binder.

[padresag]

i think that you will find that in most of the 60-66 chev and GMC trucks 1 ton and over were Napco installations.. though I imagine that one could have order Harmon,commencing in the mid 60's. they would have been outsourced to their facilities for installation befoe delivery. ford was more aligned with harmon.
late 60-early 70 is when the component business opened up in the medium and h/duty trucks. manufacturers were incorporating a lot more components and installing them. fire trucks still went to the fire truck builders ,same as buses, ambulances and other specialty builders.
I can remember specing out 2 off highway Pacific trucks in 74-75. the customer had pulled all of their specs from Hayes truck(that is what you had to bid to). you had to do it to be competitive. Pacific Truck was acquired by IHC and was disc in the 80. I think hayes must have shut down in the late 70, early 80. both grand old trucks. I was parts for IHC and went into sales
ron

[1963c-10]

Either way...I say its a good looking truck. Im interested to see it completed. And just glad to see another member here and another truck not in the salvage yard.

[padresag]

I am going to correct myself. Napco conversions as far as light duty were installed at the the factory prior to 1960 and perhaps the C30 and up after 1960

The date that NAPCO started to produce 4x4 conversion units is a little foggy. I have heard stories of GM trucks being converted as early as late 1949, but the earliest documentable truck that I have ever heard of is a 1951 Chevy 3/4 ton owned by Butch Gehrig of Odell, OR. Until October 28th of 1954, when Chevrolet introduced the '55 1st Series, all the conversions were done on 3/4 ton and larger trucks. The '54 and earlier Advance Design 1/2 ton models were not suitable for a NAPCO conversion due to the enclosed drive shaft design. GMC and Chevrolet conversions were by far the most popular, though conversions were available for Ford, Studebaker and other manufacturers.

Though the date of the first NAPCO 4x4 conversion is unknown, we do know that in July and August of 1954, NAPCO was very busy pushing its proven 4x4 conversion on truck upfitters and GMC dealers across the country. Upfitters were companies that installed upgrades and accessories like winches, auxiliary transmissions, tandem drive axles, dump bodies and hydrovac systems on stock factory trucks. The NAPCO slogan proudly stated: "Now you can have a standard Chevrolet four wheel drive pickup featuring the traction power of a tank, or, at the flip of a finger, a smoother riding, high speed, over the road truck. Aptly named the Mountain Goat, this full sized pickup will literally leap up mountains, as well as carry you through deep mud, sand, or snow."

Apparently NAPCO reached an agreement with both GMC and Chevrolet to supply them with the Powr-Pak conversion kits, and GMC began to produce 4x4 trucks on the factory assembly line (using NAPCO components) starting in 1956, with Chevrolet following suite in 1957. By the end of 1957 both GMC and Chevrolet trucks could be ordered from the factory with the NAPCO Powr-Pak conversion. The two offered identical systems other than the availability of a V-8 and an automatic transmission on the GMC trucks. The Chevy could only be ordered with the 235ci six cylinder and a four speed manual (although there was nothing stopping an owner from ordering whatever he or she wanted in a 2 wheel drive truck and then having a NAPCO Powr-Pak "upfitted" by the dealer).

Some features of this early "shift-on-the-fly" 4x4 were the unchanged turning radius, a full engine torque P.T.O. option, a rubber mounted transfer case for long, silent operation, greater ease of steering, and a guarantee of no damage to the Chevrolet or GMC frame during the three hour installation. Yes, only four holes to drill and no torch cutting! In a matter of hours, you could go from a two wheel drive to four wheel drive and the NAPCO Powr-Pak could be transferred from one GM truck to another.

If a dealer had a truck in stock that he wanted to convert to four wheel drive by using the NAPCO Powr-Pak, he could order the Powr-Pak four wheel drive package. Soon, a wooden crate, 80 inches long, 30 inches wide and 26 inches deep would show up on his loading dock weighing in at 1,410 lbs. with all the necessary parts enclosed. It also gave truck owners and dealers the distinct advantage of quickly removing the conversion package and transferring it to another truck, without damaging the originality or resale value of either vehicle (except for the four bolt holes in the frame.)

The NAPCO two speed 4x4 conversions were comprised of 85% GM parts. That meant for the most part they were serviceable by a local dealer. Complete front axle differentials, brake drums, wheels, drivelines, backing plates, springs, shock absorbers, and universal joints were all Chevrolet replacement parts, which are still available from a variety of sources today.

A 1/2-ton, two wheel drive pickup listed for $1,548.96 in late 1954. The retail price of the Powr-Pak was $995, which included a dealer freight cost of $800 from Minneapolis, Minnesota. Installation by an upfitter or equipment company included the cost of the Power-Pak, and listed at $1,248. This brought the complete list price of the finished truck to $2,796.96. These conversions were done on the 1/2 ton, 3/4 ton, one ton, and the two ton trucks, as well as the Suburbans and panels. Again, the conversion was not available for 1954 and earlier 1/2 tons because of their enclosed driveshaft design.

The first "all GM" factory 4x4's were introduced in 1960 when both Chevy and GMC went to a totally new chassis. NAPCO and its Powr-Pak conversion were left out of the equation due to the introduction of GM's completely redesigned truck line featuring independent front suspension on the two wheel drive trucks and a 4-wheel drive specific chassis on the 4-wheel drive trucks. This was the beginning of the end for the 4x4 conversion element of NAPCO. Though they did produce conversion kits for a few more years, their main business shifted to the heavier trucks, 1-1/2 ton and larger. A few later model specially built custom vehicles featuring the NAPCO components are still out there, such as Mr. Packy Pickrell's 1970 Chevy 1 ton NAPCO.

After the huge loss of the contracts with GMC and Chevrolet to supply conversion packages, NAPCO sold the rights to the Powr-Pak package to the DANA Corporation. I haven't found the date yet when that actually occurred, but we can safely assume it was after 1960. All documentation, archives, information and parts were transferred to DANA at that time. During this evolution, the association of the NAPCO name with 4x4's ceased to exist. The NAPCO 4x4 had vanished, just as it's associated history, archives and NOS parts supplies were absorbed into DANA.

During the years following the demise of the NAPCO 4x4, NAPCO has broadened its product line to include communications equipment, aircraft spare parts, logistics services and many other products and services. Due to corporate changes not related to its defense business, the company's name changed from NAPCO Industries to NAPCO International in the 1980s. Though they haven't produced the 4x4 conversion in any quantity for nearly 40 years, the company has continuously improved the efficiency, quality and breadth of its product line through deployment of new technologies, training, and hard work. They have expanded and live on today.

When asking questions or searching for any information concerning our NAPCO 4x4's, it becomes readily apparent that "all roads lead to the DANA Corporation." But why DANA, as the SPICER name is most commonly used in conjunction with NAPCO? We've heard that "DANA bought out SPICER." and that SPICER bought out NAPCO. Well, that is just NOT the case. We've got to understand just what's what in this Quest for NAPCO, and the story has all the twists and turns of a good Agatha Christy novel.

Go to Chapter 2
ron

[T Herder]

More axle info: Your rear axle is shown as a Rockwell G161, the front carrier assembly is a Rockwell E100. Ratios 5.29, 6.17, 6.80; 7.20 to 1. Unless its been changed the transfer case is listed as either a Coleman 22 or Coleman 42, both have two shifters. The difference being is the 22 operates like most common transfer cases, the 42 operates with full differential control between front and rear, which can be locked for full 4WD. Hey who knew, early full time 4WD.
Here's your front axle specs.
Best regards,
T Herder

[kenbob87]

As for the bed work...have you considered finding a long bed step side instead of lengthening a short bed. The long beds came in 8 & 9 foot length.

it is hard to tell in the picture but the bed is an 8ft box

More axle info: Your rear axle is shown as a Rockwell G161, the front carrier assembly is a Rockwell E100. Ratios 5.29, 6.17, 6.80; 7.20 to 1. Unless its been changed the transfer case is listed as either a Coleman 22 or Coleman 42, both have two shifters. The difference being is the 22 operates like most common transfer cases, the 42 operates with full differential control between front and rear, which can be locked for full 4WD. Hey who knew, early full time 4WD.
Here's your front axle specs.
Best regards,
T Herder
Attached Images

thanks a million

and thank you for all the help on this guy you really dont know how much it means to me to have complete strangers give out info on these things!

Either way...I say its a good looking truck. Im interested to see it completed. And just glad to see another member here and another truck not in the salvage yard

i agree with you it really makes me sad to see old iron like this rotting in a field or getting crushed in a junkyard. but i am really happy to be apart of this community!!! you guys have some really great info and some AWESOME trucks!!!! i will definetly be keeping you all posted on this build and im sure asking plenty of questions

[kenbob87]

oh and another thing that i find is interesting about this truck is the frame is completely straight there is no bends up or down it two channels from front to back

[63burban4x4]

Originally Posted by kenbob87

oh and another thing that i find is interesting about this truck is the frame is completely straight there is no bends up or down it two channels from front to back

again, more like a C-50 or C-60. high mounted cab, tall grille support, flared fenders, etc. Not like the blue C-40 pictured here. Unless they used the C-40 designation on both frame/cab types, that's likely larger than a C-40 IMO

Does anyone have a pic of a verified C-40 that's built like the larger trucks?

kenbob, does that cab floor have any trans hump, or is it flat? Any C-60 I've seen has a flat floor.

edit:
Actually, just saw the GMC 4000 being parted out on the parts board.......definitely a "big" truck......so I guess there's a difference between the C-40 Chevy and the GMC 4000. NEVER MIND! lol

[tincan1966]

BTW that is a bada$$ truck!

[1963c-10]

I did find numerous 67-72 c-40 big truck chevy's, and of course the GMC 4000 big trucks. But haven't found a big truck c-40. I have a ton of OEM literature at home (mostly 63, but ill look there tonight). The 67 is a c-40 the rest are GMC 4000. I have found the GMC's in verious frame lengths.

[1963c-10]

This is the only internet search pic I found of a big bolt c40

[63burban4x4]

although it's just my experience, and shouldn't be considered accurate, but I sure can't remember seeing many, if any, C-40's, while seeing plenty of C-60's and a few C-50's. I would expect that the production figures for these would roughly follow that.

clearly, the GMC 4000 is a heavier, "big" truck.

[padresag]

4000 would be classified as a medium duty truck
ron

[Corts60]

Just my opinion, but I would get the title situation sorted out before I spent any money on it. Sweet truck though.
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[kenbob87]

kenbob, does that cab floor have any trans hump, or is it flat? Any C-60 I've seen has a flat floor

no the floor is flat no transmission hump.

Just my opinion, but I would get the title situation sorted out before I spent any money on it. Sweet truck though.

im going to start getting the title thing figured out in a couple weeks when i am home again. i will figure out one way or another to get it titled though i have a bill of sale and recipt so i dont think that i will have too many problems

[Captainfab]

I don't have any pics or way of verifying, but I have seen a '64 C40 that was a medium duty truck. It had a 250 I6, SM420 trans and a single speed rear end.

[kenbob87]

well you guys asked for more pictures so here they are!

[BrutonLS1]

That truck is WICKED. It's a tank! I'm jealous. What're your plans for it? Duramax with Alison transmission?! Lol

[kenbob87]

That truck is WICKED. It's a tank! I'm jealous. What're your plans for it? Duramax with Alison transmission?! Lol

Thanks! i dont know for sure yet i am leaning towards Duramax with a 6 speed manual trans cuz i love shiftin gears lol and it would be just that much cooler! lol or i was thinking about just restoring it to stock but not sure yet there is much work needed haha