Factory 3/4t Dually???

[Joesjunk]

Im from the 67-72 side of the board, but have come across a deal on a 1978 Scottsdale/20 dually a friend of mine has. I have never seen or heard of such a thing on a 3/4ton. Here is the vin CCS248Z141836, and the GVWR is 8200. It has a 454 in it and thats what the vin shows. It has a dana70 rear end with a sway bar. It does not have cab lights though. It has the correct dually bed and everything else looks correct??? Just wanted to know if someone just swapped this stuff over a long time ago, or if this was something that was factory. Any ideas?????
Thanks!!

[LONGHAIR]

It has to be a conversion a true "Dually" is a C/30 1 ton truck.

Does it have the correct wheels on the front?
Are they on the correct hubs? or spacers?

[Joesjunk]

I forgot to get a pic, but yes, it has the correct wheels on it and the correct front hubs. It looks 100% correct, thats what I thought was weird. I thought maybe the clip had been changed at some point and it just had the wrong emblems, but the vin states its a 3/4ton. The one thing that really makes me believe it was a conversion is the fact that it does not have the roof marker lamps (standard on a 1ton). Im pretty good with info on the 67-72 trucks, but not the 73-87.
Thanks again for any info!!!

[N2TRUX]

Originally Posted by Joesjunk

... The one thing that really makes me believe it was a conversion is the fact that it does not have the roof marker lamps (standard on a 1ton)....

Joe the cab lights aren't "standard" on a dually, they are mandatory. It's a federal regulation if I am not mistaken. Regardless you can take a look at the frame and tell at a glance what going on. If it has a C-10/C20 size frame, it was not a factory dually.

[Joesjunk]

I have found a 79 1ton dually 4x4 that runs and drives good, but is rusty. I was thinking about using this 2wd truck for the body to swap over. Any issues swaping these body style trucks over??

[Dooley]

Not factory. Could be someone replaced a rusted out 1 ton cab with one off a 3/4 ton and used the donor cab ID/paperwork for registration. Could be a problem if truck gets an inspection and the title doesn't match frame ID. I've passed on buying a few trucks for this same reason. The cab roof and rear marker lights are a DOT requirement on 1 ton and larger trucks. The 4x4 cabs have the high transmission tunnel cover as some floor shift standards also have. Normal 2wd cab will need the tranny floor section modified for the 4x4.

[Joesjunk]

Where are the frame numbers on these trucks?? This thing doesnt look like it has ever been apart?

[USSkoval]

Can you get a pic of the frame rail, at the forward rear spring hanger? Oh, is it a crew cab?

[Joesjunk]

Its a regular cab. I dont have any pics of it. I might go look at it again tomorrow, if so Ill try to get pics.

[USSkoval]

IIRC, the perch spacing on a 1ton rear axle (and 3/4, crew cab ONLY) is 40.5, and 1/2 and 3/4ton are 42.5. A 1ton also got rear shocks inboard of the frame rails, and they are staggered on the opposite sides as 3/4. Look for perches and shock mounts that have been relocated on the axle, and also spring hangers and upper shock mounts that are bolted on (or welded, I suppose).

[68 TT]

My regular cab long bed 78 K20 has the Camper Special package with an 8,400 GVW rating. It also has the 40.5" rear spring spacing.

It looks kind of funny with the rear track width narrower than the front.

It also came with 5.13 gears from the factory.

If it is a 3/4-ton rated truck then it doesn't have to have the DOT mandated 1-ton roof marker lights so it could be correct. My 78 K20 is rated for a higher GVW than this dually and it does not have the roof top marker lights.

[USSkoval]

Originally Posted by 68 TT

My regular cab long bed 78 K20 has the Camper Special package with an 8,400 GVW rating. It also has the 40.5" rear spring spacing.

It looks kind of funny with the rear track width narrower than the front.

It also came with 5.13 gears from the factory.

If it is a 3/4-ton rated truck then it doesn't have to have the DOT mandated 1-ton roof marker lights so it could be correct. My 78 K20 is rated for a higher GVW than this dually and it does not have the roof top marker lights.

Interesting. Does it have the taller frame rails like a 1ton truck?

4X4 always had a narrower rear track width, btw. A single rear wheel 14ff, whether 40.5 or 42.5 perch spacing, is the same distance WMS-WMS.

[Dooley]

Originally Posted by 68 TT

My regular cab long bed 78 K20 has the Camper Special package with an 8,400 GVW rating. It also has the 40.5" rear spring spacing.

It looks kind of funny with the rear track width narrower than the front.

It also came with 5.13 gears from the factory.

If it is a 3/4-ton rated truck then it doesn't have to have the DOT mandated 1-ton roof marker lights so it could be correct. My 78 K20 is rated for a higher GVW than this dually and it does not have the roof top marker lights.

There were no factory 3/4 ton dual wheel pickups.
GM squarebody dual wheel pickups all rated at 10,000gvw with varying gcw's on trailering packages.
Available gears in 1978 were 3.73, 4.10, and 4.56 on K20 regular cab pickups.

[jeffspower]

Originally Posted by USSkoval

IIRC, the perch spacing on a 1ton rear axle (and 3/4, crew cab ONLY) is 40.5, and 1/2 and 3/4ton are 42.5. A 1ton also got rear shocks inboard of the frame rails, and they are staggered on the opposite sides as 3/4. Look for perches and shock mounts that have been relocated on the axle, and also spring hangers and upper shock mounts that are bolted on (or welded, I suppose).

Even the single wheel 1 tons have the different shock & spring perch arrangement. If it has the "wide" Camper Special rear, it is actually a 70HD in those years.

[bucket]

joe,

FWIW, i have a 78 3/4 crew cab "dually". i had always assumed it was a conversion. like yours mine appears to have been done correctly and long ago.

[Joesjunk]

Can someone tell me where the numbers are on the frame so I can check them with the vin. I bought it today (good price) But will not pick it up untill next week.

[jeffspower]

IIRC, they are on top of the upper frame lip, under the cab. LH side on a Chevy, RH side on a GMC. I think the last 6 or so digits are scattered in several places on the outsides of each vertical section.

But I could be wrong.

[jeffspower]

I went out & checked my box trailers. On my '74 it is on the left rail. On my '78 it is on the right rail. Both just a few inches in front of the rear cab mount, not stamped very deep or clear. you might need a mirror with the cab on.

Both of mine were Chevy C20's I drove before they crumbled away. Pretty sure the '74 was unmolested. Maybe the '78 was a put together, or the LH/ RH deal has to do with the vintage

[whiskeydented]

My 78 is also on the right side rail and is also stamped twice. Once where jeffspower has mentioned and also about 18 inches from that stamping towards the rear it is stamped again.

[Joesjunk]

Well, I got it home. Here are some pics of the rear axle. Im guessing the bed was changed at some point, it looks like the bed was dark blue at one time. Still a pretty clean truck, and it was cheap!!

[Joesjunk]

Pics.

[bucket]

cool truck. what are your plans for it?

[jeffspower]

Cool. I have to laugh though... you see 50,000 dollar new trucks running around on worn out rubber everyday, and this old truck has all new rubber? Maybe those guys really can't afford their trucks

I'll bet the box and chassis is original, and the cab was changed.

[Joesjunk]

My plans are to resell it. I need to see if I can find the frame numbers and see it they match the cab. The truck does have 6 brand new tires on it, But I have to give the rear tires back to the guy I bought it from. So I need 4 tires.

[bucket]

if you decide to part it, i could use the 454.