K20 vs. K30 Difference

[barrymattern]

Thanks to everyone for all the info and help in trying to figure this out – I've learned a lot in this process. I should have posted some measurements earlier, but I wasn't near the frame recently until this last weekend. Here's what I found out:

* Engine: 6.2 Liter (J code)
* Rear Leaf Sprint Count: 8 (pic attached)
* Front/Rear Brakes: 12.5", 13"
* Section Modulus: 4.53" at rear (pic attached)
* Tires: LT235/85R16

We changed the brake shoes earlier and confirmed these measurements. Based on this info, and after studying page 12 (labeled as pg. 9, pic attached) of the 1984 Chevrolet Truck Vehicle Information Kit I'm inclined to believe that the truck frame shown in the original post of this thread is a 1984 K20 with the C6P option, so that seems it would fall under an "HD" option for that year.

 

[Dano500]

Payload would vary a lot depending on the truck's options. GVW is the only way I can think of to determine if it's HD or not. The 8500 lb threshold is a gov't thing, not GM. It applies to emissions probably more than anything else. So your engine VIN may be a clue.

You could try looking at the GM Heritage center for the literature on your year truck. It will have the full listing of options, engines etc. that make up the various packages.

Now that I found out what frame modulus is, I measured and it does have the thicker modulus. I’ll research GM heritage some more.

 

[JBswth]

What you likely purchased is a 3/4 ton heavy duty. It would have the big brakes and it is rated as 8600 GVW. I have an 85 3/4 heavy duty that is all stock except for a 3 in. Body lift I put on it. The door label shows it has the 8600 GVW rating too. What this means to you is much of the drivetrain is 1ton without the dually wheels.

Hi All,

I'm newer to working on these trucks, and I'm just getting started on a project to turn my 1985 Chevy Scottsdale C10 automatic into a 4-wheel drive manual. I recently purchased a donor 1984 Chevy Scottsdale that was sold to me as a 3/4 ton K20, and the plan is to swap the '85 body onto the '84 frame. Included in the sale was an SM465 & NP205.

The other day someone who has worked on these trucks many many years almost immediately said it looks more like it's a 1-ton given how heavy duty the suspension is (their exact comment was that it looked like it was PUD, which I believe stands for Public Utility Dept). I also heard a passing comment related to the thickness of some things (didn't catch all they said as they were talking to someone else).

I have the VIN which states it's a 3/4 ton Canadian truck with a J code for the engine, which I believe is for a 6.2 diesel (engine, trans, and t-case were not included on the frame). I was also able to decode it as 8001-9001 lbs (Hydraulic only brakes), with a 2815 cargo weight rating listed in the glove box for "Truck Camper Loading Information". Based on the floor cutouts and higher center hump it looks like it was a 4-speed, and it has 8-lug wheels.

This is NOT the truck, but it does seem pretty similar: http://www.rustfreeclassics.com/Chevy4X4/84K30_SRW_RegCab_Scottsdale_White.htm

Without having the doors or other paperwork I don't have the exact build specs other than what was listed above. Taking all that into account with the pics attached here is anyone able to confirm that the frame with current suspension is indeed a 3/4 ton vs a 1 ton? Or would more exact measurements be needed? I can try to get any other info it it's needed or is more helpful.

I'm looking to learn as much as I can, and I appreciate anyone's time in taking a look at these!

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You probably purchased what originally was a Camper Special. If so, it originally had the heavy duty rear end normally found on 1 tonners.

 

[75gmck25]

My ‘75 Camper Special with 8400 lb GVW has the Camper Special option listed on the label inside the glove box door, but it also has a metal plate with loading information (max rear axle load, etc.) riveted on the inside of the drivers side door frame. Does your truck have any similar data plate?

 

[barrymattern]

You probably purchased what originally was a Camper Special. If so, it originally had the heavy duty rear end normally found on 1 tonners.

I think you're right – after spending quite a bit of time researching the vehicle information kit all the specs I'm seeing on my frame match that C6P option. Kinda surprised the full float rear end wasn't included given all the other HD upgrades

 

[barrymattern]

My ‘75 Camper Special with 8400 lb GVW has the Camper Special option listed on the label inside the glove box door, but it also has a metal plate with loading information (max rear axle load, etc.) riveted on the inside of the drivers side door frame. Does your truck have any similar data plate?

Good to know about the glove box door and metal plate – the truck didn't have doors when I purchased it so I'm missing a lot of option information. There was a label on the inside of the glove box, but I didn't see the option code listed on it, unfortunately