Question for the Pros

[Shagydelic86]

The current owner of the truck has owned the truck since 2003. So definitely nothing was done to it since then as far as modifying other things. He bought it from an elderly farmer that used it prior to that who he believes was the original owner of the vehicle.

 

[CSFJ]

I believe pre '81 4x4 crew cabs had a 12 bolt front diff... just like Suburbans. Pretty hard to call that a K30...?

There were no 3/4 4x4 crew cabs. If you wanted a 4x4, you went to the 1 ton and got the dana 60 front.

 

[Craig 85]

This is a C20 3+3 that was mostly converted to a C30. If the driver door is original, it specifies 16x6.5" wheels, Duallys were 16x6". The truck also has vacuum assist brakes and has a GVW of 8600 LBS. Duallys had 10k GVW and hydroboost brakes. Based on how close the rear drums are to the springs I would guess the rear end is the narrowed chassis cab rear end. I can't read the other door tag, but it gives the production date of the truck on the upper left of the tag. The last clue that tells me its a 3/4 ton is there is no provision in the roof for marker lights.

Either way, it looks like it would be a fun project.

 

[Shagydelic86]

Thanks everyone for all the helping in identifying this thing! I’ve learned a ton in the short term that I’ve found this thing for sale. The owner did finally say that he vaguely remembers the original owner said a shop in KC would convert 3/4 trucks into duallies and said that this was one of them. So if he is accurate in his memory. The mystery could be solved. Either way, I do believe I’m gonna move on it. It’s the best one I have found for the price.

I will ask one more question. I know it’s a personal opinion and different for everyone but I’d like to get an idea. I’m buying the truck for $3k. Thoughts? I drove it yesterday. Has good oil pressure. Didn’t over heat. Floors are solid. Small bits of rust in door jams that you can see.

Thanks again.

RHP

 

[CSFJ]

Not a bad price. Probably one of the more reasonable prices I've seen lately.

 

[Shagydelic86]

Not a bad price. Probably one of the more reasonable prices I've seen lately.

I tend to agree. I've seen some of these things go for way more in a lot worse shape. So I can't complain about it!

RHP

 

[Old77]

Thanks everyone for all the helping in identifying this thing! I’ve learned a ton in the short term that I’ve found this thing for sale. The owner did finally say that he vaguely remembers the original owner said a shop in KC would convert 3/4 trucks into duallies and said that this was one of them. So if he is accurate in his memory. The mystery could be solved. Either way, I do believe I’m gonna move on it. It’s the best one I have found for the price.

I will ask one more question. I know it’s a personal opinion and different for everyone but I’d like to get an idea. I’m buying the truck for $3k. Thoughts? I drove it yesterday. Has good oil pressure. Didn’t over heat. Floors are solid. Small bits of rust in door jams that you can see.

Thanks again.

RHP

Pretty reasonable at 3k. I'd say that's a solid price based on what your impressions of it after a test drive.

 

[scwaters]

frankentruck. Mines a K10 but a major FT.

 

[bucket]

There were no 3/4 4x4 crew cabs. If you wanted a 4x4, you went to the 1 ton and got the dana 60 front.

Recent discoveries showed me that there were factory built 3/4 ton 4x4 crew cabs in '75 and '76 only. The frames looked like the '77 and newer frames, just with a D44 up front. The SPID will show an option called "4x4 Crew Cab". I don't recall the rpo number, but I have it saved. They were made available because of some pipeline project somewhere, and some company must have had a lot of pull at GM.

You must be registered for see images attach

 

[CSFJ]

Interesting.

 

[scwaters]

As an owner of a Frankentruck I have been attempting to discover what year frame and drivetrain are from. The above post mentioned a change in the frame design between 76 and 77. My cab is from a 76 and the motor is a factory installed crate so that’s no help ( I have run the numbers through this forum to know avail.) I have spent hours searching for the frame ID number also without success. Can anyone either explain or show the difference between the 76 and 77 frame?

 

[fussfeld]

i would pass, but that's just me.

 

[PrairieDrifter]

The other thing I just noticed is the bed is from the 70's as it exposed gas caps and doesn't have gas doors. I'm not sure when the actual change was made, but I know my '79 1/2 ton had fuel doors and so did my '80 C20 3+3. One other detail to look for is hydro boost on the brakes. 1 tons had them.

From what I’ve seen gas doors are a hit and miss through the 70’s, I’ve seen earlier ones with them while later ones don’t and vice versa it’s all over the place really lol. My 79 has gas doors but also has dual tanks. My buddy’s 77 had them as well but he just picked up a 79 c10 diesel that I’m pretty sure doesn’t have doors I can’t remember now.

But also with that 79 it’s a 350 olds diesel and an olds th400, but it’s a c10 and has hydroboost, so that doesn’t seem like a good indicator to me. Maybe it had hydro boost just because it’s diesel? I’m not sure.

 

[CSFJ]

From what I’ve seen gas doors are a hit and miss through the 70’s, I’ve seen earlier ones with them while later ones don’t and vice versa it’s all over the place really lol. My 79 has gas doors but also has dual tanks. My buddy’s 77 had them as well but he just picked up a 79 c10 diesel that I’m pretty sure doesn’t have doors I can’t remember now.

But also with that 79 it’s a 350 olds diesel and an olds th400, but it’s a c10 and has hydroboost, so that doesn’t seem like a good indicator to me. Maybe it had hydro boost just because it’s diesel? I’m not sure.

Diesels don't have a natural vacuum, so hydro boost is pretty standard. the only diesel offered prior to the 6.2 in '81(?) was the olds engine. Boxes get swapped around so much, it's not uncommon to get some confusion. Iirc, '77ish was the year they switched.

 

[PrairieDrifter]

Diesels don't have a natural vacuum, so hydro boost is pretty standard. the only diesel offered prior to the 6.2 in '81(?) was the olds engine. Boxes get swapped around so much, it's not uncommon to get some confusion. Iirc, '77ish was the year they switched.

Wasn’t sure if vacuum pumps were the go to or not. I don’t mess with the diesels much at all, we used to have a 6.2 c10 on the farm but that was about it lol